Dietary caffeine, performance and mood: enhancing and restorative effects after controlling for withdrawal reversal.
This study aimed to determine whether sustained (i.e. dietary) use of caffeine has net effects on performance and mood compared with sustained abstinence, and whether dietary caffeine restores performance and mood adversely affected by sleep restriction. Participants (n = 96) alternated weekly between ingesting placebo and caffeine (1.75 mg/kg) three times daily for 4 consecutive weeks, while either rested or sleep restricted. Performance involved either a single task requiring sustained vigilance or a varied battery of brief psychomotor and cognitive tasks, and mood was assessed using the Profile of Mood States. Caffeine had no significant net enhancing effects for either performance or mood when participants were rested, and produced no net restorative effects when performance and mood were degraded by sleep restriction.
James
Jack E
JE
National University of Ireland, Galway, Ireland. j.james@nuigalway.ie
Gregg
M Elizabeth
ME
Kane
Marian
M
Harte
Frances
F
D000293:Adolescent; D000328:Adult; D000339:Affect / Q000187:drug effects*; D001143:Arousal / Q000187:drug effects; D002110:Caffeine / Q000009:adverse effects / Q000493:pharmacokinetics / Q000494:pharmacology*; D000697:Central Nervous System Stimulants / Q000009:adverse effects / Q000493:pharmacokinetics / Q000494:pharmacology*; D004032:Diet; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011597:Psychomotor Performance / Q000187:drug effects*; D011930:Reaction Time / Q000187:drug effects; D012463:Saliva / Q000378:metabolism; D012727:Sex Characteristics; D012892:Sleep Deprivation / Q000188:drug therapy / Q000523:psychology; D013375:Substance Withdrawal Syndrome / Q000523:psychology*
D000697:Central Nervous System Stimulants; D002110:Caffeine