Working the night shift means living in a way that counteracts how our bodies operate. The human body’s internal body clock, called the circadian rhythm, is programmed to sleep at night and be awake during the day. Defying this system by working at night can lead to disruptive gastrointestinal problems and other forms of ill health. However, recent research in the journal Nutrients shows that one technique can provide some relief to the nearly 15 million Americans workers who don’t work the traditional 9-to-5.
While many night shift workers are tempted to either eat full meals or skip eating entirely, a new study published on June 15 shows that if you want the best chance at thriving during the night shift, very light snacking is the way to go.
The Australian-based team of researchers note that there’s a high rate of long term-gastrointestinal diseases like irritable bowel syndrome among night shift workers, as well as a high risk of weight change and obesity. Short-term gastric symptoms like bloating, gas, and epigastric pain are common as well.
Other research shows that flight attendants who eat during the night shift are more likely to report stomach aches, bloating, and constipation. In a similar study, nurses who also ate during the night shift reported the same symptoms. Nurses involved in another study avoided eating altogether during their night shift in order to avoid these problems and maintain alertness.
The Nutrients study aims to shed some light in a sector of the workforce that hasn’t adopted specific recommendations about meal size, timing, or overall eating behavior. Forty-four participants, 26 of them male, participated in a simulated shift work experiment that involved living at the University of South Australia Sleep and Chronobiology Laboratory for a week. This lab is windowless, sound attenuated, and time-isolated.
Prior to the first-day shift, participants were kept awake for 28 hours — a process designed to simulate “the period of extended wakefulness commonly reported by shift workers prior to the first night in a series of nightshifts.” Then, for the next four days, they began sleeping seven hours during the day, then waking at around 5 p.m. for their “night shift.” The last day was used as a recovery day and overall transition back into the real world.
During wake times, participants had the option to do activities like watch movies and play board games. They were monitored by research assistants, and they weren’t allowed access to electronic devices that could provide any cues about what time it was in the world beyond the lab.
Importantly, the group was randomly split into three test-eating conditions. At 12:30 a.m., the participants were given either a meal (like a sandwich, a muesli bar, and an apple), a snack (just the apple), or no food at all. These were the only food options available until 7 a.m. Participants in the “no eating” condition ate their dinner at 7 p.m. then “worked” before their breakfast at 7 a.m. They snacked again at 9:30 a.m., then slept before another snack at 5 p.m.
Throughout the waking hours, the participants reported how hungry they were, how sleepy or fatigued they felt, and whether or not they felt any headaches, dizziness, bloating, or stomach pain. Research assistants also took samples of the participants’ blood, saliva, and hair.
While the snack group and the no-dinner group were significantly hungrier than the dinner group, there was no difference in desire to eat between those who had a snack or a meal. This suggests that “although the snack did not lead to feeling of fullness, participants did not want to eat more after eating the snack.”
Furthermore, the group that ate dinner at 12:30 a.m. was more likely to report feelings of dizziness and headaches than either of the other groups. The snacking group appeared to achieve the best of both worlds: They were less hungry, thought less about food, and reported fewer feelings of uncomfortable fullness and sleepiness than the meal group.
The study authors emphasize that what could be giving these snacking participants an advantage over real-life night shift workers is that they only snacked once and at a specific time.
“Perhaps in the real world shift workers who report gastric upset are consuming greater amounts of food and eat later in the shift, nearer to the trough of gut function,” they write. Real shift workers are also more likely to eat unhealthy snacks, smoke, and consume caffeine — all of which harm gastrointestinal health.
The reason that eating at night causes discomfort likely links back to our biological clocks, which previous research has shown have a distinct effect on digestive organs. Disrupting the circadian rhythm disrupts metabolism, and when metabolites — the products of metabolism — are thrown off their own rhythm, the operations of the liver, pancreas, and digestive tract become disrupted.
Now, the same research team want to assess exactly which snacks are the best for night shift workers to eat. The goal is to help shift workers be alert, safe, and healthy — and eating cookies and drinking coffee throughout the night isn’t likely the best way to do that, as tempting as it is to fuel yourself with sugar and caffeine.
Shiftworkers report eating during the night when the body is primed to sleep. This study investigated the impact of altering food timing on subjective responses. Healthy participants (n = 44, 26 male, age Mean ± SD = 25.0 ± 2.9 years, BMI = 23.82 ± 2.59kg/m2) participated in a 7-day simulated shiftwork protocol. Participants were randomly allocated to one of three eating conditions. At 00:30, participants consumed a meal comprising 30% of 24 h energy intake (Meal condition; n = 14, 8 males), a snack comprising 10% of 24 h energy intake (Snack condition; n = 14; 8 males) or did not eat during the night (No Eating condition; n = 16, 10 males). Total 24 h individual energy intake and macronutrient content was constant across conditions. During the night, participants reported hunger, gut reaction, and sleepiness levels at 21:00, 23:30, 2:30, and 5:00. Mixed model analyses revealed that the snack condition reported significantly more hunger than the meal group (p < 0.001) with the no eating at night group reporting the greatest hunger (p < 0.001). There was no difference in desire to eat between meal and snack groups. Participants reported less sleepiness after the snack compared to after the meal (p < 0.001) or when not eating during the night (p < 0.001). Gastric upset did not differ between conditions. A snack during the nightshift could alleviate hunger during the nightshift without causing fullness or increased sleepiness.