0216 The Effect Of Caffeine On Glucose Metabolism, Self-reported Hunger And Mood State During Extended Wakefulness

Abstract

Abstract Caffeine is a stimulant often taken to reduce sleepiness and improve cognitive performance. The effect of caffeine on glucose metabolism during sleep deprivation is less well understood. This double-blind laboratory study examined the impact of caffeine on glucose metabolism, self-reported hunger and mood state during 50h of wakefulness. Participants were assigned to caffeine (n=9, 6M, age 21.3 +/- 2.1y; BMI 21.9 +/- 1.6kg/m2 ) or placebo conditions (n=8, 4M, age 23.0 +/- 2.8y; BMI 21.8 +/- 1.6kg/m2 ). Following a baseline sleep opportunity from 22:00h-08:00h, participants commenced 50h of extended wake. Caffeine (200mg) or placebo gum was administered at 01:00h, 03:00h, 05:00h and 07:00h during each night of extended wake. Continual glucose monitoring was used to capture interstitial glucose 2h post-breakfast, from which area under the curve (AUC) was calculated. Hunger and mood state were assessed at 10:00h, 16:30h, 22:30h and 04:30h. A significant rise in glucose AUC, in response to breakfast, was seen following the second night of extended wakefulness ( p =0.003, n 2 partial =0.32, large effect). Caffeine did not alter the glucose response, with no difference shown between conditions ( p =0.680, n 2 partial =0.01, small effect). Participants reported significant ( p <0.020) increases, with large effect sizes, for tiredness ( n 2 partial =0.68), mental exhaustion ( n 2 partial =0.61), irritability ( n 2 partial =0.35) and stress ( n 2 partial =0.48) on the second night of extended wakefulness compared to the first night. On the first, but not the second night ( p< 0.044), caffeine mitigated the rise in impairment, with medium-large effect sizes for the condition*night interaction for tiredness ( n2 partial =0.40), mental exhaustion ( n2 partial =0.14) and irritability ( n2 partial = 0.23). Self-reported hunger was not affected by extended wake or caffeine. Caffeine improved performance and reduced self-reported tiredness, mental exhaustion, and irritability under conditions of extended wake. However, the effectiveness appeared to be limited after 45 hours. Caffeine did not alter glucose metabolism over and above the effect of extended wakefulness. This work was funded by Australian Defence Acquisition Project Land-121 and supported by the Defence Science and Technology (DST) Group. The US Army Medical Research and Material Command supported this work.