Subjects arrived in the laboratory in groups of three to four each on the evening before the sleep deprivation period began. All subjects were required to refrain from caffeine and alcohol ingestion for 72 h prior to the beginning of the study. Blood and urine samples were taken to ensure that the subjects were free of caffeine and other drugs of abuse.

They were trained on a computerized performance assessment battery Thorne et al. Eleven electrodes were attached to the scalp and face by using the international 10—20 system of electrode placement.

Electroencephalograms EEGs , electrooculograms EOGs , and submental electromyograms EMGs were recorded continuously by using an 8-channel Oxford Medilog ambulatory cassette recorder.

Dinner was provided between training sessions. Subjects retired at h. The sleep deprivation period began upon awakening the next morning at h day 1. They remained awake for the next Subjects were monitored continuously by the staff to prevent unintentional sleep and were provided with books, games, movies, music tapes, conversation, and occasional brief walks to occupy them between tests.

At h following 49 h of sleep deprivation , subjects were administered placebo or one of three doses of caffeine, USP anhydrous City Chemical Corporation, New York, N. Caffeine was administered orally by having the subjects drink ml of an artificially sweetened lemon juice drink in which the caffeine powder was dissolved.

Placebo consisted solely of the sweetened lemon juice drink. All doses were given in a double-blind manner. These tasks were administered every 2 h through the sleep deprivation period and at 1, 2, 3, 4, 6, 8, 10, and 12 h after caffeine administration. Code Substitution and Recall. A code key that paired the digits 1 through 9 in a one-to-one correspondence with letters was presented to the subjects.

Below the key, a letter appeared and subjects had to press the key of the correct number. The code key disappeared after 27 pair presentations; if needed, they could see it again by pressing 0. Fifty-four pairs were presented. Recall was assessed after the subject completed the rest of the battery tasks about 15 min later.

Subjects had to press a number in response to each of nine letter presentations; no code key was available during the recall testing. Logical Reasoning. A task of logical reasoning ability was adapted from Baddeley The letter pair AB or BA was presented along with a statement that correctly or incorrectly described the order of the letters within the pair e.

The 32 possible permutations were presented once each in random order. Sustained Attention. The task was a machine-paced mental arithmetic task requiring sustained attention and concentration.

Two randomly selected digits and either a plus or a minus sign were displayed sequentially in the same center screen location followed by a prompt symbol:? The subject performed the indicated addition or subtraction and entered the least significant digit of the result.

If the result was negative, the subject first added 10 to it and entered the single positive digit that was the remainder. The digits and signs were each presented for ms and were separated by ms, with the next trial beginning ms after the response. The task ended after 50 responses and typically took 3 to 4 min.

Subjects viewed a 6-by-6 block of squares with 36 red and green squares arranged in random order each block contained an equal number of red and green squares. This task of immediate recall allowed subjects to view the arrangements for as long as they liked and then press a key to present two choices, one of which matched the original set of squares.

They were required to pick the correct matching square. Twenty trials were presented. Reaction Time. A choice reaction time task was used to measure reaction time. The visual-motor task required subjects to press the numbered keyboard keys corresponding to numbers presented on the screen.

The digits 0 through 9 appeared one at a time in the center of the screen. The stimulus remained on until a response was made. Fifty numbers were presented. Profile of Mood States. The Profile of Mood States POMS McNair et al.

Subjects rated themselves on each adjective from 1 not at all to 5 extremely. Visual Analog Scales VAS. Subjects rated themselves with a mark along a line mm in length.

They were heart pounding, headache, sweaty, and upset stomach. The POMS and VAS were completed five times during the sleep deprivation period prior to drug administration at and h on days 1 and 2 and at h on the morning of day 3 2 h before caffeine administration.

POMS and VAS ratings were taken at 1, 2, 4, 8, and 12 h after drug administration. Multiple Sleep Latency Tests. Each modified multiple sleep latency test MSLT was conducted by having the subjects lie in bed in a darkened, sound-attenuated room with their eyes closed.

They were instructed to relax and allow themselves to fall asleep. EEGs, EOGs, and EMGs were displayed on a Grass Electroencephalograph model 8—10D for on-line scoring of awake versus sleep during the MSLT.

An experimenter awakened a subject after 30 s of stage 2 sleep or the onset of rapid eye movement REM. The test was terminated at 20 min if sleep had not occurred. MSLTs were conducted at , , , , , and h on days 1 and 2 of the sleep deprivation period. MSLTs were conducted eight times on day 3 at 1.

Stanford Sleepiness Scale. For the Stanford Sleepiness Scale SSS Hoddes et al. The SSS was completed approximately every 2 h throughout the sleep deprivation period at , , , , , , , , , , and h on days 1 and 2. The SSS was completed eight times on day 3 at 1, 2, 3, 4, 6, 8, 10, and 12 h after drug administration.

Measurements of blood pressure, heart rate, and oral temperature were taken at least every 2 h throughout the sleep deprivation period. After caffeine administration, measurements were taken at 15, 30, 60, 90, , , , and min and then hourly until 13 h after drug administration.

Blood samples were collected prior to and at 15, 30, 60, and 90 min, and 2, 2. Results are reported elsewhere Eddington et al. Separate two-factor repeated measures analysis of variance by using the General Linear Model SAS Institute, Cary, N.

were performed for each dependent variable and POMS subscale. The two factors were group or dose and time. First, each dependent variable was analyzed for group differences and effects of the sleep deprivation period prior to the drug administration by using all measurements made prior to drug administration.

Second, each dependent variable was analyzed for the effects of drug and time after drug administration by using the last value obtained prior to drug administration and all values obtained after drug administration.

Statistical results thus reported for the main effects of drug dose, the main effects of time, and an interaction between these main effects. Significant main effects were further evaluated by the Newman-Keuls Multiple Range Test. For each of the tasks, three measures of performance were analyzed: accuracy percent correct , speed responses per unit of time , and throughput number of correct responses per unit of time.

The throughput measure takes both accuracy and speed of performance into account and was subjected to statistical testing. Predrug means include data for all subjects; there were no differences between the groups prior to drug administration. Performance, Mood, and Physiology Analysis of Variance Summary.

Performance on the choice reaction time task for 8 h after drug administration in subjects who received the mg dose was significantly different from that in subjects who received the placebo.

The mg dose improved performance for 4 h. For subjects receiving the mg dose, performance was not significantly different from that for subjects receiving the placebo at any point following administration.

For subjects receiving the mg dose, performance remained significantly better than that for subjects receiving placebo for 10 h after drug administration, with no significant differences observed among the dose groups at the final h testing period.

Performance on the logical reasoning task by subjects receiving the two highest doses of caffeine was significantly better than by subjects receiving placebo for the entire h period. In addition, caffeine restored performance to the levels obtained after rest during this interval.

Performance after administration of the mg dose was significantly different from that after administration of placebo for 6 h after drug administration. The effects of sleep deprivation on mood, as measured by the POMS and VAS, are reported in more detail elsewhere Penetar et al.

Briefly, the scores of all six subscales of the POMS changed significantly as a result of the sleep deprivation. Similarly, ratings on the VAS showed the effects of sleep deprivation. Following caffeine administration, significant increases in the POMS vigor subscale and significant decreases in the POMS subscales of fatigue and confusion were observed Table 20—1.

Vigor ratings for all three dose groups were significantly different from those for the placebo group for 2 h after caffeine adminstration. Vigor ratings for the mg dose group were 97 percent of those for subjects in the rested condition 1 h after caffeine administration and remained at 84 percent of those for subjects in the rested condition at the 2-h measurement.

Conversely, fatigue ratings for all three caffeine dose groups decreased significantly for 2 h following caffeine administration. Confusion ratings in the mg dose group were significantly decreased in comparison with those in the placebo group 2 h after caffeine administration.

Caffeine reversed the sleep deprivation effects reported in subjective ratings of alertness for 2 h, energy levels for 12 h, confidence for 2 h, sleepiness for 12 h, and talkativeness for 2 h following drug administration. Caffeine significantly increased self-rated anxiety for 2 h, and jitteriness or nervousness for 12 h following drug administration.

Ratings of heart pounding, headache, sweatiness, and upset stomach were unaffected by caffeine. For the rested condition day 1 , mean sleep latency periods were between Latency to stage 2 sleep following caffeine administration. Average values of the Stanford Sleepiness Scale increased gradually from 1.

Caffeine's effects were significant for 2 h after drug administration and were not dose-related i. Diastolic blood pressure and oral temperature were significantly affected by caffeine administration Table 20—1 and Figure 20—3.

At 1 h after admini stration, both the and the mg doses significantly increased diastolic blood pressure in comparison with the placebo; there were no significant differences at other time points.

The mg dose of caffeine significantly increased oral temperature in comparison with placebo at several measurement times after administration: 2, 2. Neither systolic blood pressure nor pulse was significantly affected. Time course of caffeine effects on four vital signs.

Caffeine was observed to have significant effects on diastolic blood pressure at 1 h and oral temperature from 2 to 12 h after drug administration. See text for details. The study described here indicates that caffeine is effective in reversing the performance degradations and the alterations in mood and alertness produced by periods of prolonged sleep deprivation.

The results indicate that these beneficial effects can be long-lasting and not at the expense of serious mood or physiological side effects. Sleep deprivation degrades cognitive performance. The effects of caffeine on performance in non-sleep-deprived volunteers have been well documented, even at the low dose levels commonly found in food and drink products see Lieberman [] for a review.

The study described here extends the usefulness of caffeine, showing that large doses up to mg are effective in improving a variety of cognitive performances in sleep-deprived individuals, and outlines the time course of its effects in these individuals.

The tasks used in the present study were chosen to sample a variety of cognitive abilities with varying mental demands.

Choice reaction time requires little thinking but does require great accuracy and speed. Caffeine produced improved performances of all three tasks, with performance returning to those of rested subjects for up to 12 h after caffeine administration. Caffeine was not observed to affect recall or code substitution tasks.

In toto, these results are in concert with those presented previously Lieberman, ; Roache and Griffiths, and document for the first time the relatively long-lasting effects of this drug on cognitive performance. The study described here shows that caffeine compares favorably with amphetamine in reversing the effects of sleep deprivation on cognitive performance.

Using an identical sleep deprivation paradigm, Newhouse et al. Sleep deprivation also alters mood and degrades alertness.

The present study documents the fact that caffeine can have significant beneficial effects in reversing these mood changes; sleepiness and confusion declined, whereas increases in energy and confidence levels were reported.

Although there were increased ratings of anxiety and jitteriness or nervousness, these effects were not severe and did not elicit complaints from the subjects.

Depending on the measure, alertness, which was severely degraded by 49 h of sleep deprivation, was improved for 2 to 4. In this regard, caffeine was not as effective as amphetamine. The alertness of amphetamine treated subjects 20 mg , as measured by sleep latency tests, was nearly restored to the levels of rested subjects for 7 h Newhouse et al.

Caffeine's effects on alertness are therefore less potent and shorter acting than amphetamine's. Caffeine's effects on physiological measures are important for assessing its usefulness as a stimulant.

The study described here shows that relatively high doses of caffeine are well tolerated by sleep-deprived individuals and that its effects are similar to those found in other studies in non-sleep-deprived subjects given lower doses than those used in the present study Myers, ; Newcombe et al.

Additionally, there were no changes in self-reports of other side-effects heart pounding, headache, sweatiness, upset stomach. Of note was caffeine's observed effect on oral temperature.

Oral temperature normally rises during the day, from a low in the early morning hours to a peak in the early evening hours.

The subjects in the present study showed this typical response. Caffeine increased temperatures above the normal rise throughout the observation period, again revealing an important aspect of its effects and duration of action. The significance of this effect awaits further experimentation, although this type of effect has been observed previously with another stimulant, d -amphetamine Newhouse et al.

The authors thank the staff of the Behavioral Biology, in particular Sharon Balwinski and Kevin Peyton, for assistance in the conduct of the experiment described here. Investigators adhered to AR 70—25 and USAMRDC Reg 70—25 on the use of volunteers in research.

Use of trade names does not constitute endorsement of product. The views of the authors do not purport to reflect the position of the Department of the Army or the Department of Defense. HARRIS LIEBERMAN: We have some unpublished data from a couple of studies in which we did find significant effects of caffeine on mood swing.

We did not use doses as low as 32 milligrams but used doses of 64 and milligrams of caffeine. Effects on performance by doses lower than those are hard to detect, but over the long run, over a series of studies, my feeling is that there really are effects with low dosages, and those are the doses that we typically take in our background.

JOEL GRINKER: I was just curious whether in any of the caffeine studies or in any of the other supplement studies age has been looked at systematically as a factor. I have two thoughts, one, that in fact it might potentiate the ability of older individuals or that in fact it has less effectiveness, and I wonder if you have any comments.

DAVID PENETAR: I have here one study that related to age. Typically, these studies were done, with young, healthy males. HARRIS LIEBERMAN: We did look at the age parameter in one of our caffeine studies, but we did not see any significant differences as a function of age or gender.

Do you find much variation that would indicate that shortness of sleep time versus onset of sleep, etc. Are they uniform in your subjects or are they highly individualistic? DAVID PENETAR: What we do is we bring them into the study the night before and give them 9 hours of time in bed before we start the study, so at that time they are all pretty consistent in the amount of sleep that they have had.

Do you find a uniform effect in terms of delay of sleep or shortness of length of sleep, etc? DAVID PENETAR: We did not specifically look at that because by the time they went to bed it was over 12 hours after they had received caffeine. WILLIAM WATERS: A couple of questions. One pertaining to the onset of parameters.

Did you have a look at whether or not you have any data or whether or not sleep can be induced prior to that? WILLIAM WATERS: It could be that what you had was a referral of something that might allow it to occur.

The other thing was, under the influence of caffeine, did you notice any change in the number, the length, stage one, and arousals? DAVID PENETAR: Again, by the time our subjects went to bed, it was over 12 hours after they had received the caffeine, and we did not see any changes; there were no differences between the groups.

We did monitor them. We recorded them through their sleep, and we saw no differences in sleep architecture, time of sleep, time to bed, or sleep efficiency; we saw no differences for 12 hours. JOHANNA DWYER: I worked with a neurologist who was interested by some observations years ago, when they did a lot more electroconvulsive shock than they do now.

Apparently, they used to prime the patients with caffeine, and by doing this, they could use a lower level of shock and still get the same effect.

The reason I bring it up here is not because I hope anyone here is heavily into this, but rather, are there other changes in the electroencephalograms in terms of caffeine's effects that may be in addition to what we have been talking about?

ALLISON YATES: Just one thing. I noticed in some of the graphs that it almost looked as if at milligrams the subjects might have had even a little bit better performance than they had initially in their first 24 hours. This result is important in considering enhancement of performance with normal subjects.

HARRIS LIEBERMAN: Yes, two slides that you showed with my studies, the vigilance and reaction times, were for subjects who had stayed up all night the night before and who were back in the morning after the administration. Their performances were similar to those with placebos under the same conditions.

I consider that to be above normal, although since caffeine is such a common component of the diet, it is hard to untangle it all. HARRIS LIEBERMAN: We typically include that as a parameter in our studies and look to see whether there are differences between moderate, low, and heavy caffeine users in their responsiveness, and in the low and moderate range there is not much difference.

When you get to the real high users, you see big differences in responsiveness. That depends on the timing of administration, whether they are in a deprivation stage, or whether they are already on a lot caffeine.

HARRIS LIEBERMAN: Average caffeine consumption is about milligrams per day, which is maybe three cups of not very strong coffee.

I define high for the purpose of categorizing subjects as above or milligrams per day. We used to always think that members of the Army must be heavy coffee drinkers because you get that perception, but looking out in field studies where soldiers are eating rations, we found out that even though you gave a meal ready-to-eat, 90 percent of the coffee packets were returned unused.

The rest of the 10 percent probably went mostly to the senior sergeants, who had a chance to stay by the talking place and make some coffee for themselves. So young soldiers in the field today are not heavy coffee drinkers. I am sure they drink plenty of caffeine if they have carbonated beverages.

But most of the time carbonated beverages are not available to them in the field, although maybe in Desert Storm cans of Coke manged to get inside of the tanks anyway. My question is, has anybody done sleep studies on evaluating caffeine using the vehicle of delivering the caffeine in the form of a cola or in the form of a coffee beverage itself?

DAVID PENETAR: A number of studies look at coffee drinking when they give caffeine. In fact, in some of the studies reported here, they took decaffeinated coffee and added caffeine to it, and the subjects drank it that way.

In other studies it was either caffeine pills or caffeine powder dissolved in some drink. For instance, I am sure your subjects knew when they were receiving a placebo.

DAVID PENETAR: Ours was powdered caffeine dissolved in a lemon juice drink, and the lemon juice drink was very bitter. As you know, caffeine powders are very bitter, so they could not tell what they were drinking other than lemon juice drink.

WILLIAM BEISEL: So many of the emergency rations and so on seem to be candy bars with chocolate flavoring. How much of that is caffeine?

DAVID PENETAR: Milk chocolate has about 7 milligrams per ounce, whereas bakery chocolate or unsweetened chocolate has about 35 milligrams per ounce.

They figure that, for example, a Hershey's candy bar has 25 to 35 milligrams per ounce, so it is not a lot, and it is less than most sodas. Penetar, Walter Reed Army Institute of Research, Washington, D. Subjects were paid for their participation. The investigators adhered to AR 70—25 U.

Department of the Army, and U. Army Medical Research and Development Command Reg 70—25 , on the use of volunteers in research. Turn recording back on. National Library of Medicine Rockville Pike Bethesda, MD Web Policies FOIA HHS Vulnerability Disclosure. Help Accessibility Careers.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation. Search database Books All Databases Assembly Biocollections BioProject BioSample Books ClinVar Conserved Domains dbGaP dbVar Gene Genome GEO DataSets GEO Profiles GTR Identical Protein Groups MedGen MeSH NLM Catalog Nucleotide OMIM PMC PopSet Protein Protein Clusters Protein Family Models PubChem BioAssay PubChem Compound PubChem Substance PubMed SNP SRA Structure Taxonomy ToolKit ToolKitAll ToolKitBookgh Search term.

Show details Institute of Medicine US Committee on Military Nutrition Research; Marriott BM, editor. Contents Hardcopy Version at National Academies Press. Search term. EFFECTS OF CAFFEINE ON MOOD AND ALERTNESS Several questionnaires and methods have been used to assess caffeine's effects on mood.

MATERIALS AND METHODS Subjects Fifty normal, healthy, nonsmoking, drug-free males between the ages of 18 and 32 mean age, Procedure Subjects arrived in the laboratory in groups of three to four each on the evening before the sleep deprivation period began.

Mood Measures Profile of Mood States. Alertness Measures Multiple Sleep Latency Tests. Vital Signs Measurements of blood pressure, heart rate, and oral temperature were taken at least every 2 h throughout the sleep deprivation period.

Catecholamine and Caffeine Assays Blood samples were collected prior to and at 15, 30, 60, and 90 min, and 2, 2. Statistical Analysis Separate two-factor repeated measures analysis of variance by using the General Linear Model SAS Institute, Cary, N.

RESULTS Performance Tests For each of the tasks, three measures of performance were analyzed: accuracy percent correct , speed responses per unit of time , and throughput number of correct responses per unit of time. TABLE 20—1 Performance, Mood, and Physiology Analysis of Variance Summary.

Mood Measures The effects of sleep deprivation on mood, as measured by the POMS and VAS, are reported in more detail elsewhere Penetar et al. Alertness Measures Multiple Sleep Latency Tests For the rested condition day 1 , mean sleep latency periods were between FIGURE 20—2 Latency to stage 2 sleep following caffeine administration.

Stanford Sleepiness Scale Average values of the Stanford Sleepiness Scale increased gradually from 1. TABLE 20—2 Stanford Sleepiness Scale Scores.

Vital Signs Diastolic blood pressure and oral temperature were significantly affected by caffeine administration Table 20—1 and Figure 20—3. FIGURE 20—3 Time course of caffeine effects on four vital signs.

Doses of mg are needed to reverse severely degraded performance as a result of long periods of sleep deprivation. Presumably, lower doses — mg would be effective in ameliorating the changes caused by shorter periods of deprivation.

Use of caffeine should be restricted to special situations when sleep has been unusually disrupted and for the benefit of temporarily 10—12 h restoring alertness and sustaining performance during critical periods of military operations.

Finally, although caffeine can temporarily sustain performance during continuous operations, it should be emphasized that no drug can substitute for adequate sleep.

See U. Department of the Army. Babkoff, H. Mikulincer, T. Caspy, R. Carasso, and H. Sing a The implications of sleep loss for circadian performance accuracy.

Work Stress — Sing, D. Thorne, S. Genser, and F. Hegge b Perceptual distortions and hallucinations reported during the course of sleep deprivation.

Perceptual Motor Skills — Baddeley, A. A 3-minute test based on grammatical transformations. Psychonomic Sci. Battig, K. Buzzi, J. Martin, and J. Feierabend The effects of caffeine on physiological functions and mental performance.

Experentia — Bruce, M. Scott, M. Lader, and V. Marks The psychopharmacological and electrophysiological effects of single doses of caffeine in healthy human subjects.

Chait, L. Griffiths Effects of caffeine on cigarette smoking and subjective response. Childs, J. Caffeine consumption and target scanning performance.

Factors — Choi, O. Shamin, W. found a decreasing risk of suicide with increasing coffee consumption. There was no association between decaffeinated coffee and suicide risk, suggesting that caffeine was the key factor, rather than plant compounds in coffee. There is consistent evidence from epidemiologic studies that higher consumption of caffeine is associated with lower risk of developing PD.

The caffeine in coffee has been found in animal and cell studies to protect cells in the brain that produce dopamine. In that time, after adjusting for known risks of PD, those who drank at least 10 cups of coffee a day had a significantly lower risk of developing the disease than non-drinkers.

Women showed the lowest risk when drinking moderate intakes of cups coffee daily. The authors stated the need for larger studies with longer follow-up periods.

Gallstones There are various proposed actions of caffeine or components in coffee that may prevent the formation of gallstones.

Mortality In a large cohort of more than , participants followed for up to 30 years, an association was found between drinking moderate amounts of coffee and lower risk of early death. Both caffeinated and decaffeinated coffee provided benefits.

The authors suggested that bioactive compounds in coffee may be responsible for interfering with disease development by reducing inflammation and insulin resistance. The protective effect was present regardless of a genetic predisposition to either faster or slower caffeine metabolism.

Instant and decaffeinated coffee showed a similar health benefit. What about iced coffee? Caffeine Caffeine is naturally found in the fruit, leaves, and beans of coffee, cacao, and guarana plants.

It is also added to beverages and supplements. Learn about sources of caffeine, and a review of the research on this stimulant and health. References Je Y, Liu W, and Giovannucci E. Coffee consumption and risk of colorectal cancer: a systematic review and meta-analysis of prospective cohort studies.

International Journal of Cancer , Eskelinen MH, Kivipelto M. J Alzheimers Dis. Grosso G, Godos J, Galvano F, Giovannucci EL. Coffee, Caffeine, and Health Outcomes: An Umbrella Review. Annu Rev Nutr. van Dam RM, Hu FB, Willett WC. Coffee, Caffeine, and Health.

Coffee consumption and risk of endometrial cancer: findings from a large up-to-date meta-analysis. International Journal of Cancer. Arab L. Epidemiologic evidence on coffee and cancer.

Nutrition and Cancer , Ding M, Bhupathiraju SN, Chen M, van Dam RM, Hu FB. Caffeinated and decaffeinated coffee consumption and risk of type 2 diabetes: a systematic review and a dose-response meta-analysis. Diabetes Care. Jiang X, Zhang D, Jiang W.

Coffee and caffeine intake and incidence of type 2 diabetes mellitus: a meta-analysis of prospective studies. Eur J Nutr. Lopez-Garcia E, Rodriguez-Artalejo F, Rexrode KM, Logroscino G, Hu FB, van Dam RM. Coffee consumption and risk of stroke in women.

de Koning Gans JM, Uiterwaal CS, van der Schouw YT, et al. Tea and coffee consumption and cardiovascular morbidity and mortality. Arterioscler Thromb Vasc Biol.

Crippa A, Discacciati A, Larsson SC, Wolk A, Orsini N. Coffee consumption and mortality from all causes, cardiovascular disease, and cancer: a dose-response meta-analysis.

Am J Epidemiol. Ding M, Bhupathiraju SN, Satija A, van Dam RM, Hu FB. Long-term coffee consumption and risk of cardiovascular disease: a systematic review and a dose-response meta-analysis of prospective cohort studies. Ding M, Satija A, Bhupathiraju SN, Hu Y, Sun Q, Han J, Lopez-Garcia E, Willett W, van Dam RM, Hu FB.

Association of Coffee Consumption With Total and Cause-Specific Mortality in 3 Large Prospective Cohorts. Lara DR. Caffeine, mental health, and psychiatric disorders. Guo X, Park Y, Freedman ND, Sinha R, Hollenbeck AR, Blair A, Chen H. Sweetened beverages, coffee, and tea and depression risk among older US adults.

PLoS One. Wang L, Shen X, Wu Y, Zhang D. Coffee and caffeine consumption and depression: A meta-analysis of observational studies. Aust N Z J Psychiatry. Coffee, caffeine, and risk of completed suicide: results from three prospective cohorts of American adults.

World J Biol Psychiatry. Costa J, Lunet N, Santos C, Santos J, Vaz-Carneiro A. Sääksjärvi K, Knekt P, Rissanen H, Laaksonen MA, Reunanen A, Männistö S. Eur J Clin Nutr. Ascherio A, Zhang SM, Hernan MA, Kawachi I, Colditz GA, Speizer FE, Willett WC. Ann Neurol. Panza F, Solfrizzi V, Barulli MR, Bonfiglio C, Guerra V, Osella A, Seripa D, Sabbà C, Pilotto A, Logroscino G.

Coffee, tea, and caffeine consumption and prevention of late-life cognitive decline and dementia: a systematic review. J Nutr Health Aging. Santos C, Costa J, Santos J, Vaz-Carneiro A, Lunet N. Caffeine intake and dementia: systematic review and meta-analysis.

Carman AJ, Dacks PA, Lane RF, Shineman DW, Fillit HM. Leitzmann MF, Willett WC, Rimm EB, et al. A prospective study of coffee consumption and the risk of symptomatic gallstone disease in men. Leitzmann MF, Stampfer MJ, Willett WC, Spiegelman D, Colditz GA, Giovannucci EL.

Coffee intake is associated with lower risk of symptomatic gallstone disease in women. Loftfield E, Cornelis MC, Caporaso N, Yu K, Sinha R, Freedman N. Association of Coffee Drinking With Mortality by Genetic Variation in Caffeine Metabolism: Findings From the UK Biobank.

JAMA Intern Med. Moderate caffeine consumption during pregnancy. Committee Opinion No. American College of Obstetricians and Gynecologists.

Obstet Gynecol ;—8. Loading Comments Email Required Name Required Website.

Some may contain herbal supplements, such as ginseng and guarana, which may be used to increase energy and mental alertness.

Use caution with these substances, as research on safety and effectiveness is limited. Also, some herbal supplements can interact with prescriptions, so seek input from your health care professional before consuming. Place peaches and mint in the bottom of a large heatproof pitcher. Muddle with a wooden spoon until the peaches are pulpy and broken down.

Hang tea bags in the pitcher and pour in boiling water. Let steep for at least 20 minutes. Remove the tea bags. Refrigerate the tea until cold. Fill glasses generously with ice.

Strain the tea and pour over the ice. Garnish with mint if desired. Nutrition information per serving: 14 calories; 0 g fat 0 g saturated fat ; 6 mg sodium; 3 g carbohydrate; 1 g fiber; 1 g protein; 47 mg caffeine. Freeze coffee in an ice cube tray until firm, at least 4 hours or overnight.

Combine the frozen coffee cubes, milk, cocoa, maple syrup and vanilla in a blender. Pulse until smooth, adding plain ice cubes if you want it thicker. Divide between 2 glasses. Dust with a little cocoa powder, if desired.

Serve immediately. Tip: Double-strength coffee or espresso gives you the best coffee flavor when making blended or iced coffee drinks. To brew double-strength coffee, use twice the amount of grounds as you normally would for a regular cup of coffee.

Espresso is strong enough when brewed regularly. Nutrition information per serving: calories; 2 g fat 1 g saturated fat ; 74 mg sodium; 25 g carbohydrate; 2 g fiber; 5 g protein; mg caffeine. Jamie Pronschinske , is a dietitian in La Crosse , Wisconsin.

Skip to main content. Posted By. Jamie Pronschinske, RDN, CD Nutrition. Recent Posts. It is present in many foods and drinks, which makes it is easy to forget that it is a drug. It is even an ingredient in beverages and foods that are marketed to children.

While caffeine has some health benefits, it does have significant negative effects on the body and brain. Unlike many other psychoactive drugs , caffeine is legal and is one of the most widely used substances in the world. Also Known As: Because caffeine is legal, slang terms are generally not used when referring to it.

Slang terms for coffee and tea, two of the most common naturally caffeinated beverages, include Joe and cuppa. Drug Class: Caffeine is classified as a stimulant. It increases activity in the central nervous system. Common Side Effects: Caffeine can increase energy levels and alertness, but side effects can include irritability, jitters, anxiety , rapid heart rate, and insomnia.

Caffeine is an alkaloid found in a wide variety of plants including coffee beans, tea leaves, and cocoa beans. It is found both naturally and as an additive in many food and drink items including coffee, tea, chocolate, and soft drinks.

On its own, caffeine has no flavor and does not have any nutritional value. Note that while Food and Drug Administration FDA regulations stipulate products containing added caffeine must be labeled, labeling is not required for food and beverages that naturally contain the stimulant.

Since many products do not specify how much caffeine they contain, it can be difficult to know how much caffeine you are consuming. Because caffeine acts as a central nervous system CNS stimulant, people usually take it to feel more alert and energetic.

Caffeine can improve mood and help people feel more productive. It is believed to work by blocking the neurotransmitter adenosine's receptors, increasing excitability in the brain. Research has shown that caffeine can have both positive and negative effects on health.

It can improve mental performance—up to a point. In a study published in , caffeine was shown to improve performance on a range of different tasks including vigilance, response times, information processing, and some—but not all—proofreading tasks. But it's no shortcut to improving your performance.

When comparisons are made between people whose daily intake of caffeine is low up to mg caffeine per day and those who regularly consume a lot of caffeine more than mg caffeine per day , the improvements are quite small and don't get better with more caffeine.

While people who use a lot of caffeine every day do show improved performance with more caffeine, it may be that they are simply counteracting the effects of caffeine dependence—so by taking more caffeine, they are getting closer to what their performance would be if they weren't addicted to caffeine in the first place.

Caffeine might improve reaction times, but expectations may also play a role. According to a review published in , caffeine improves vigilance and reaction times. Another study published in explored the subtleties of how this works and found that at least some of the time, this is an expectancy effect.

Expectancy effects play a significant role in the effects that drugs have on people's perceptions and behaviors. People's expectancies of how caffeine will affect their performance—in particular, if they think it will impair their performance—seems to underlie some of these improvements.

In other words, if people think consuming caffeine will make their performance worse, they try harder and compensate for the expected effects of caffeine. At recommended doses, caffeine can have a beneficial effect on mood.

Caffeine influences neurotransmitters that play a role in mood and mental performance including norepinephrine, dopamine, and acetylcholine. Research published in found that drinking two to three cups of caffeinated coffee each day was linked to a lower risk of suicide.

While the FDA and other health groups have recommended limits for caffeine consumption for adults, they have not established a safe level for children. The American Academy of Pediatrics discourages caffeine use by children and adolescents.

The American College of Obstetricians and Gynecologists ACOG recommends that pregnant women limit their caffeine intake to less than mg per day. Caffeine is sometimes prescribed or used off-label to improve mental alertness in patients experiencing fatigue or drowsiness.

Caffeine citrate is also used as a short-term treatment for breathing problems in premature infants. Caffeine can improve alertness, but it can also lead to a number of unpleasant side effects, including:. Caffeine can also affect:. Mood : While people often use caffeine to improve mood, excessive caffeine consumption can increase anxiety.

Heart rate : Caffeine speeds up the heart rate with significant effects occurring after consuming mg, the equivalent of about three and a half cups of brewed coffee.

In higher doses, caffeine can cause more significant effects on the heart by changing the speed and regularity of your heartbeat. This is known as tachycardia or cardiac arrhythmia and can be serious. Blood pressure : Caffeine consumption may raise blood pressure. This effect of caffeine, known as the "pressor effect," is evident across age and gender groups, and is particularly pronounced in people with hypertension high blood pressure.

If you are unsure of whether this applies to you, ask your doctor about your blood pressure and get their advice on moderating your caffeine intake accordingly.

When caffeine is consumed in large quantities, the side effects can range from unpleasant to severe, sometimes even resulting in caffeine overdose. Caffeine can also pose dangers when taken with other substances including alcohol.

Caffeine use can result in excessive alcohol consumption since the stimulant effects of caffeine mask the depressant effects of alcohol.

Since it is not an illicit drug, people rarely try to disguise their caffeine consumption. There are signs that someone might be overusing caffeine, including:. Caffeine overdose can lead to symptoms such as chest pain, confusion, hallucinations, convulsions, and trouble breathing.

If someone is experiencing these symptoms, contact emergency services immediately. Some people think caffeine improves their memory. According to a review published in , the research evidence for this is mixed, although a number of studies found improved memory was associated with using energy drinks.

People also often wonder if excess caffeine consumption might contribute to heart problems. While caffeine use does have short-term effects on heart rate, it is unclear whether larger intakes increase the risk of cardiovascular problems in the longer term.

According to a review, several studies have indicated no increased risk for cardiovascular problems in either men or women related to caffeine intake, but caffeine may be problematic for people with high blood pressure. However, if you have any type of heart disease, you should speak with your doctor before consuming any caffeinated foods and beverages.

A common misconception is that caffeine use can cause infertility. A study published in suggests that there is no link between consuming low amounts of caffeine around mg per day or less and fertility problems.

Another common question is whether caffeine pills and other high-dose products are different from food and beverages containing caffeine.

Products that contain high concentrations of caffeine such as pills and powders, while not chemically different from other forms of the stimulant, do pose additional dangers.

Because these products are so concentrated, the difference between a safe and toxic dose is difficult to measure, which increases the risk of accidental overdose and negative side effects such as seizures.

Repeated consumption of caffeine can lead to tolerance, dependence, and withdrawal. Tolerance takes place when you must consume larger or more frequent doses in order to have the same effects. Dependence involves needing to keep taking the substance in order to ward off unpleasant withdrawal effects.

Caffeine reaches peak levels in the body about an hour after consumption, but you may continue to feel these stimulating effects for up to six hours. While using caffeine can lead to becoming physically or psychologically dependent on it, it does not have strong enough of an effect on the brain's reward system to result in a true addiction.

The National Institute on Drug Abuse NIDA defines addiction as the chronic, uncontrollable use of a substance despite negative consequences. However, people often casually refer to their love of coffee and other caffeine-containing beverages as an "addiction.

While caffeine is not considered addictive, caffeine intoxication is recognized as a disorder in the DSM Caffeine intoxication is defined as the consumption of more than mg of caffeine followed by at least five symptoms that can include restlessness, excitement, insomnia, diuresis, stomach upset, tachycardia, psychomotor agitation.

These symptoms must result in significant distress and impairment in functioning and must not be due to another medical condition. People often continue to use caffeine as a way to reduce any negative symptoms of caffeine withdrawal that they might experience.

The short-term benefit you may get from caffeine can be offset by increased anxiety while you are under the influence of caffeine, and when the effects wear off, withdrawal symptoms may worsen the very mental processes you are hoping to improve. Caffeine withdrawal usually begins within 12 to 24 hours after consuming the last dose.

It can lead to a number of unpleasant withdrawal effects including:. Withdrawal symptoms can range from mild to more severe depending on how much caffeine you are used to consuming. These unpleasant effects usually begin to subside within two or three days.

If you use a lot of caffeine—drinking the equivalent of more than three cups of tea or coffee per day—it may be negatively affecting your health, so lowering your intake is worth considering. The best approach is to gradually taper your caffeine consumption. Doing this lowers your dependence gradually while minimizing the negative effects of withdrawal.

It is important to be aware of all of the different sources of your intake, including foods, energy drinks, caffeine, tea, and soft drinks.

Try eliminating these sources progressively by replacing them with lower-caffeine or caffeine-free alternatives. Talk to your doctor if you are concerned about your caffeine use, or contact SAMSHA at to find mental health services in your area.

Meredith SE, Juliano LM, Hughes JR, Griffiths RR. Caffeine use disorder: A comprehensive review and research agenda. J Caffeine Res. Richards G, Smith AP.

A review of energy drinks and mental health, with a focus on stress, anxiety, and depression.