The impact of meal timing on performance, sleepiness, gastric upset, and hunger during simulated night shift

Crystal Leigh GRANT, Jillian DORRIAN, Alison Maree COATES, Maja PAJCIN, David John KENNAWAY, Gary Allen WITTERT, Leonie Kaye HEILBRONN, Chris DELLA VEDOVA, Charlotte Cecilia GUPTA, Siobhan BANKS

This study examined the impact of eating during simulated night shift on performance and subjective complaints. Subjects were randomized to eating at night (n=5; 23.2±5.5y) or not eating at night (n=5; 26.2±6.4y). All participants were given one sleep opportunity of 8h (22:00h-06:00h) before transitioning to the night shift protocol. During the four days of simulated night shift participants were awake from 16:00h-10:00h with a daytime sleep of 6h (10:00h-16:00h). In the simulated night shift protocol, meals were provided at ≈0700h, 1900h and 0130h (eating at night); or ≈0700h, 0930h, 1410h and 1900h (not eating at night). Subjects completed sleepiness, hunger and gastric complaint scales, a Digit Symbol Substitution Task and a 10-minute Psychomotor Vigilance Task. Increased sleepiness and performance impairment was evident in both conditions at 0400h (p<0.05). Performance impairment at 0400h was exacerbated when eating at night. Not eating at night was associated with elevated hunger and a small but significant elevation in stomach upset across the night (p<0.026). Eating at night was associated with elevated bloating on night one, which decreased across the protocol. Restricting food intake may limit performance impairments at night. Dietary recommendations to improve night-shift performance must also consider worker comfort.