Caffeine effects on recovery sleep following 27 h total sleep deprivation.
BACKGROUND
Caffeine is widely used to reverse alertness and performance decrements. However, caffeine's effects on subsequent recovery sleep and post-recovery performance are not well documented and, therefore, were evaluated.


METHODS
Six habitually low (LC: < or = 100 mg x d(-1)) and three habitually high (HC: > or = 400 mg x d(-1)) caffeine users completed a randomized crossover design. After 20 h of wakefulness, repeated doses of caffeine gum [0 (placebo) mg, 100 (low dose) mg, or 300 (high dose) mg] were administered at 03:00, 05:00, and 07:00. At 10:00 (27 h sleep deprivation) subjects slept for 8 h, followed by Psychomotor Vigilance Task (PVT) administration at 33 and 65 min post-awakening.


RESULTS
Low dose caffeine increased stage 1 minutes only. However, high dose caffeine impaired sleep maintenance (reduced total sleep time/increased wake) and reduced sleep depth (increased stage 1 minutes/percentage and slow-wave sleep (SWS) latency, and reduced SWS minutes during the first third of the sleep period). With high dose caffeine, LC users had less SWS percentage as compared with HC users. The HC users had reduced stage 2 percentage with high dose caffeine as compared with placebo and low dose caffeine. Caffeine dose and habitual caffeine use did not influence post-recovery sleep PVT performance.


CONCLUSIONS
Caffeine exerts mild deleterious dose-response effects on recovery sleep following total sleep deprivation, primarily early in the sleep period, with potential recovery from these effects after sufficient sleep as suggested by lack of post-recovery sleep performance deficits. Habitual caffeine use appears to minimally reduce caffeine effects.
LaJambe
Cynthia M
CM
Department of Behavioral Biology, Division of Neurosciences, Walter Reed Army Institute of Research, Silver Spring, MD, USA. CML149@psu.edu
Kamimori
Gary H
GH
Belenky
Gregory
G
Balkin
Thomas J
TJ
D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D002110:Caffeine / Q000494:pharmacology*; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D017286:Polysomnography; D011597:Psychomotor Performance / Q000187:drug effects* / Q000502:physiology; D011930:Reaction Time / Q000187:drug effects; D012892:Sleep Deprivation / Q000188:drug therapy*; D012894:Sleep Stages / Q000187:drug effects; D014851:Wakefulness / Q000187:drug effects* / Q000502:physiology
D000697:Central Nervous System Stimulants; D002110:Caffeine