Introduction: Sustained operations are common in military and emergency services. In these operations it is not always possible to obtain sleep, resulting in sleep deprivation. Caffeine is a widely used fatigue countermeasure. However, the impact of caffeine on glucose metabolism, hunger, and satiety during sleep deprivation is largely unknown.
Methods: In this double-blinded laboratory based study, participants were assigned to either a caffeine (n=12, 4F, 22.5±3.3y, 21.7±1.5kg/m2) or placebo condition (n=12, 5F, 22.5±2.5y, 22.3±2.1kg/m2). The protocol included one baseline sleep (22:00h–08:00h), 50h sleep deprivation and a daytime recovery sleep (10:00h–19:00h). Caffeine (200mg) or placebo gum was chewed for 5min at 01:00h, 03:00h, 05:00h and 07:00h during each night of sleep deprivation. Meal timing and composition were controlled throughout the study; breakfast composition ≈1611kJ; 16% protein, ≈73% carbohydrate and 3% total fat. Interstitial continual glucose monitors captured 2h post-breakfast levels, at 5min intervals. Hunger/satiety scales were administered at 10:00h after 26h of sleep deprivation.
Results: Relative to baseline (6.1± 0.5mmol/L) sleep deprivation led to increased mean glucose 2h post breakfast at 24h sleep deprived (6.5±0.5mmol/L, p<0.001) and 48h sleep deprived (7.1±0.5mmol/L, p<0.001). There was no difference between placebo and caffeine conditions (p=0.743) on glucose levels. Hunger increased (p=0.001) while satiety decreased (p=0.014) after 26h sleep deprivation. Caffeine did not moderate this effect (hunger p=1.000, satiety p=0.484).
Conclusions: Results suggest that sleep deprivation impairs glucose metabolism, increases hunger and reduces satiety. Chewing caffeine gum did not influence this effect.
Funding Source: Defence Science and Technology Organisation, Australian Government, Department of Defence