Effects of sleep or food deprivation during civilian survival training on cognition, blood glucose and 3-OH-butyrate.

OBJECTIVES

The study was designed to compare effects of food deprivation (FD) and sleep deprivation (SD) on cognition during survival training.

METHODS

In a cross-over design (n=12), the effects of FD (up to 66 hours followed by 500 kcal intake over 24 hours) and SD (up to 50 hours) on cognitive variables, blood glucose, and 3-OH-butyrate were studied.

RESULTS

Food deprivation and SD impaired attention-dependent tasks. The FD impairment of simple reaction time was independent of blood glucose levels, which were normalized by a 500 kcal intake over 24 hours while the reaction time was not. Sleep deprivation and FD impaired maze-solving performance on all variables except rule breaks, which were significantly occurring after 50 hours of SD. Delayed word recall was impaired by SD for 50 hours. On the Balloon Analogue Risk Task, SD was associated with reduced risk-taking. In a gambling task, both SD for 50 hours and FD for 66 hours were associated with a tendency to make early choices when presented with consecutive choices, but the risk-taking was not affected.

CONCLUSIONS

Sleep deprivation has multiple cognitive effects, including attention, memory, visual-spatial ability, and risk-taking. Food deprivation had no affect on risk-taking, while the other tasks were affected in a way similar to SD but were less pronounced. The FD effects on cognition did not appear to depend on blood sugar levels. The need to sleep should be prioritized in survival situations to avoid cognitive impairment.