Sleep, caffeine effects

The adverse effects of caffeine are a common experience to most caffeine consumers. Too much caffeine results in uncomfortable to adverse central nervous system effects, or neurotoxicity. The effects include restlessness, tension, and mild tremor or the jitters and may progress to feelings of anxiety and even fear. Regular caffeine users soon learn how to manage their caffeine consumption to maintain blood caffeine at a desirable level that produces mild stimulation without the uncomfortable neurotoxic effects. Fortunately, the half-life of caffeine is short, so that any undesirable effects soon decline. Many people also experience insomnia from caffeine consumption. Caffeine s effect on sleep varies from individual to individual. Some people can consume caffeine late in the evening and sleep well, but for other people consumption of caffeine late in the day affects sleep. It is important to understand your own individual response to caffeine. 

A recent report by the Committee on Military Nutrition Research (81) recommended using caffeine doses of 100-600 mg to sustain the cognitive performance and physical endurance of military personnel, especially during periods of sleep deprivation. The Committee noted the fact that caffeine s effects appear particularly consistent in fatigued individuals. 

The contradictions that abound in the experimental findings about tolerance to caffeine are probably a result of poor research methods, such as not specifying caffeine-use patterns in subjects (Curatolo Robertson, 1983). In general, tolerance probably does develop to caffeine s effects on renal function, sleep, and other physiological functions, such as blood pressure and heart rate. On the other hand, little tolerance seems to develop to caffeine s stimulant effects (Hogan, Hornick, Bouchoux, 2002). 

Caffeine is considered by pharmacologists to be a mild stimulant of the central nervous system. It has been shown to promote feelings of well being and increased abiUty to perform certain mental tasks efficiently. There are people who are oversensitive to the effects of caffeine overindulgence by these individuals, eg, intake of more than 600 mg caffeine/d, can bring unwanted effects such as anxiety, restlessness, sleeping difficulties, headache, or palpitations of the heart (54). 

ENHANCING SLEEP PATTERNS. To promote the effects of the sedative or hypnotic the nurse provides supportive care, such as back rubs, night lights or a darkened room, and a quiet atmosphere. The patient is discouraged from drinking beverages containing caffeine, such as coffee, tea, or cola drinks, which can contribute to wakefulness. 

Rosenthal, L., Roehrs, T., Zwyghuizen-Doorenbos, A., Plath, D., et-al., Alerting effects of caffeine after normal and restricted sleep. Neuropsychopharmacology 4(2), 103-108, 1991. 

Penetar, D., McCann, U., Thorne, D. and Kamimori, G., Caffeine reversal of sleep deprivation effects on alertness and mood. Psychopharmacology 112(2-3), 359-365, 1993. 

Beaumont, M., Batejat, D., Coste, O. et al. (2005). Recovery after prolonged sleep deprivation residual effects of slow-release caffeine on recovery sleep, sleepiness and cognitive functions. Neuropsychobiology 51 (1), 16-27. 

De Valck, E., De Groot, E. Cluydts, R. (2003). Effects of slow-release caffeine and a nap on driving simulator performance after partial sleep deprivation. Percept. Mot. Skills 96 (1), 67-78. 

Rogers, P. J., Heatherley, S. V., Hayward, R. C. et al. (2005). Effects of caffeine and caffeine withdrawal on mood and cognitive performance degraded by sleep restriction. Psychopharmacology 179 (4), 742-52. 

Virus, R. M., Ticho, S., Pilditch, M. Radulovacki, M. (1990). A comparison of the effects of caffeine, 8-cyclopentyltheophylline, and alloxazine on sleep in rats. Possible roles of central nervous system adenosine receptors. Neuropsychopharmacology 3 (4), 243-9. 

Wesensten, N. J., Killgore, W. D. Balkin, T. J. (2005). Performance and alertness effects of caffeine, dextroamphetamine, and modafinil during sleep deprivation./. Sleep Res. 14 (3), 255-66. 

Yanik, G., Glaum, S. 8r Radulovacki, M. (1987). The dose-response effects of caffeine on sleep in rats. Brain Res. 403 (1), 177-80. 

Some CNS stimulants have an effect on the same systems that are involved in wakefulness, including glutamate-, NE-, DA-, 5-HT-, histamine-, hypocretin- and ACh-containing neurons. This group includes molecules such as cocaine, amphetamine, and nicotine. The sleep-promoting systems are concentrated in the medial part of the brainstem, dorsal reticular substance of the medulla, anterior hypothalamus, and basal forebrain (Jones 2005). Other stimulants, such as caffeine and theophylline, block some sleep-inducing mechanisms. Modafinil is also a CNS stimulant with an unknown mechanism of action. 

Lagarde D., Batejat D., Sicard B. et al (2000). Slow-release caffeine a new response to the effects of a limited sleep deprivation. Sleep 23, 651-61. 

Traffic Safety Administration. Since drowsiness is the brain s last step (-(->) before falling asleep, driving while drowsy can—and often does—lead to disaster. Caffeine and other stimulants cannot overcome the effects of severe sleep deprivation. The National Sleep Foundation says that if you have trouble keeping your eyes focused, if you can t stop yawning, or if you can t remember driving the last few miles, you are prob-(25) ably too drowsy to drive safely. 

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