The Effect of Meal Frequency and Glycemic Index During the Night Shift on Alertness, Hunger, and Gastrointestinal...

Nutrition strategies for night-shift workers could optimize alertness and minimize hunger and reduce gastrointestinal complaints, enhancing safety and well-being.

This study aimed to investigate the effects of 1 or 3 small meals, with either low or high glycemic index (GI), compared with no meal, on alertness, hunger, and gastrointestinal complaints during the night shift.

Fifty-one female health care workers, aged 18 to 61 y, participated in a 2-armed randomized crossover design. In 1 study arm, participants received 1 yogurt meal during the night shift, AND in the other, they received 3. Each study arm involved 3 intervention periods during night shifts, with participants consuming yogurt with low GI (1LGI or 3LGI) OR high GI (1HGI or 3HGI) carbohydrates, or no meal (0NGI). Objective alertness was assessed using a validated brief psychomotor vigilance task (PVT-B), subjective alertness with the Samn-Perelli scale, and hunger and gastrointestinal complaints through questionnaires.

Participants in the 1LGI (β: -4.6; 95% CI: 0.0, 9.3) and 3LGI (β: -3.4; 95% CI: 0.0, 6.8) conditions had fewer lapses during the PVT-B than those in the 3HGI condition. No differences were found between meal conditions for median and reciprocal reaction time or subjective alertness. All 4 conditions reported less hunger (β: from -0.6 to -1.2) compared with no meal. The 3LGI condition resulted in more rumbling intestines than the 3HGI (β: 1.1; 95% CI: 0.4, 1.7) and 0NGI (β: 0.74; 95% CI: 0.11, 1.37) conditions.

Our study suggests that consuming 3 small low GI meals during the night shift helps maintain alertness and reduces lapses compared with 3 high GI meals. It also minimizes hunger but may cause mild gastrointestinal complaints. This trial was registered at International Clinical Trial Registry (https://trialsearch.who.int/Trial2.aspx?TrialID%3dNL-OMON25574).