Night shifts offer a litany of nutritional challenges. Most research tends to focus on the nutritional practices of individuals during shift work. But what about when the titillating highs of being run off your feet in an understaffed hospital gives way to the sweet release of the almighty post-call day? Let’s talk nutrition, psychology and why on earth you chose shift work as a life choice.

Sleep: A Phenomenon Reserved for Non-Shift Workers

Have you ever been post-call?

No.

Do you want me to describe it to you?

Being post-nightshift is akin to being hungover and jetlagged, with bucketload of self-loathing thrown in. This does not foster a rested, mentally-stable individual ready to face the day. Carpe diem? Au contraire. Carpe DM sugar daddies, amirite healthcare workers?

Sleep deprivation, restriction and disturbance are the holy trinity of shift work, and their biological impact on hunger levels is a big old yikes for us shift workers.

In their 2021 meta-analysis, Chang and Peng noted an association between night shift work, a longer time to fall asleep and increased waking after sleep onset ^[1]. Sleeping during the day is not “natural” to us, and our circadian rhythms are not wired for sleeping during the day, which can make it a challenge to get to sleep. In addition, for many of us, our environment isn’t well set-up for restful sleep. It is naturally brighter during the day and  people who don’t work nights are living their lives (which creates noise). This can make achieving high-quality, restful sleep a challenge.

Alterations to sleep can have knock-on effects for our appetite. Insufficient sleep is associated with interruption to leptin metabolism ^[2]. Leptin plays a role in inhibiting our appetite. A decrease in leptin levels associated with reduced sleep may lead to us feeling hungrier and overeating post-call ^[3]. Similarly, sleep restriction is associated with elevated ghrelin, the hormone linked with stimulating appetite ^[4]. Couple that with interrupted sleep on-call (AKA getting phone calls about BS exams), the post-call worker is not exactly primed for optimal appetite/hunger regulation.

Tiredness also creates a barrier to good nutritional choices. When you are exhausted, meal-prepping can seem like too much effort. Doing a weekly shop when you can barely see is not likely to go well. Consequently, the post-call individual may find themselves reaching for the path of least resistance – the almighty post-call takeaway. Which of course isn’t necessarily cause for panic, but chronic, excessive consumption of these less nutrient-dense options can lead to some problems down the line.

The (Circadian) Rhythm is Gonna Get Ya

I’m not going to go into too much detail on circadian rhythm and chrononutrition, as I have covered it in several previous posts (XXX). If you want a more in-depth overview of circadian rhythm and chrononutrition, I will direct you to this review article ^[5]. TLDR; shift work will reef your circadian rhythm around. Big yikes.

Circadian misalignment (CM) may contribute to dysmetabolism of several hormones related to appetite. This potentially differs between the sexes. One study reported no effect of CM on 24 hour leptin and ghrelin levels. However, during the waking period, both genders reported elevated ghrelin levels. Females also reported reduced leptin, and higher ghrelin levels ^[6]. Overall, CM encourages alterations in normal appetite hormone levels ^[7].

Whilst other reviews denote the need to further investigate this relationship ^[8], literature is generally conclusive that CM is associated with an elevated consumption of “unhealthy” energy-dense foods ^[7,8,9]. This hedonic drive for hyperpalatable foods may promote overeating in the lowly post-call shift worker.

You Followed the Advice, You Idiot

I know I said I wasn’t going to get too much into chrononutrition, but my insatiable desire to prove a point knows no bounds.

Sacrificing your circadian rhythm to the health service is a noble pursuit. However, following the chrononutrition advice generally provided to shift workers may also inadvertently lead to overeating the following day. Nobody wins with shift work.

Owing to the potential deleterious impact of elevated post-prandial glucose and triglyceride levels ^[10,11], nightshift workers are typically advised to eat meals early on in the shift, and limit eating during the biological night.

We are also advised to limit eating too close to bedtime, so that we can sleep better ^[12] (N.B. all of these studies note a need for further research).

That’s all well and good. However, cutting off your food intake halfway through your “waking period”, and obviously not eating during your “sleep period” is potentially a long fasting window for the nightshift worker. Extended fasting periods may lead to increased appetite in some individuals, which can also lead to overeating ^[13].

Poor Nutritional Habits

Many of us shift workers don’t help ourselves either. There are several studies showing evidence of poor dietary habits amongst shift workers. One study reported that shift workers are more likely than day workers to skip main meals, eat less “meals”, eat less veg and eat meals later on in the day ^[14]. Similarly, Cain et al. ^[15] reported a preference for high-calorie, high-fat foods following nightshift workers in comparison with non-shift workers.

These practices tend to promote overeating. Meal skipping can lead to elevated hunger at night, which is a big yikes for overeating. Choosing energy-dense foods with less nutrients is also unlikely to help curb the biological drive to overeat. Of course, it can be a challenge to overcome these habits, but we must accept some level of personal responsibility.

As tempting as it is to blame shift work for all of our dietary woes, sometimes we are the villain.

Recommendations

So, how can we help ourselves overcome this biological drive to overeat?

• Practice good sleep hygiene. Obviously, in an ideal world we would get restful, uninterrupted sleep post-call. In the real world, we need to help ourselves. Investing in blackout blinds, a good eye mask and “borrowing” earplugs from the MRI department can all enhance sleep quality.
• Limit caffeine intake close to sleeping. It can be tempting to mainline caffeine to get you through the last few hours of your shift, but it’s never going to help you sleep well after your shift. It’s best to suffer on uncaffeinated, if overeating is something you struggle with post-call.
• Do a food shop before your shift. Let’s face it, you’re not fit for the general public in a supermarket post-call. Don’t kid yourself. If possible, do your food shopping before your night shift, so you have some healthier options to hand post-call.
• Don’t skip meals. When you first wake up after your night, try and eat as soon as possible. You might feel like death, we all do, but eating a high-protein breakfast/lunch after waking can help reduce overeating later on.
• Have options. Much like dating, when post-call, it is important to have a number of options to hand. We want to make healthy options the lowest -hanging fruit (immaculate pun if I say so myself). Having meals or snacks pre-prepared or requiring minimal preparation can be really beneficial, and help reduce the allure of a takeaway.
• Quit. I will never not advocate for quitting shift work. Take me with you.

References

1. Chang WP, Peng YX (2021) Meta-analysis of differences in sleep quality based on actigraphs between day and night shift workers and the moderating effects of age. J Occ Health 63.
2. Mosavat M, Mirsanjari M, Arabiat D et al. (2021) The Role of Sleep Curtailment on Leptin Levels in Obesity and Diabetes Mellitus. Obes Facts 14, pp. 214-221.
3. Copinschi G (2005) Metabolic and endocrine effects of sleep deprivation. Ess Psychopharm 6(6), pp. 341-347.
4. Cooper CB, Neufeld EV, Dolezal BA et al. (2018) Sleep deprivation and obesity in adults: a brief narrative review. BMJ Open Sport Ex Med 4(1).
5. Flanagan A, Bechtold DA, Pot GK et al. (2020) Chrono-nutrition: From molecular and neuronal mechanisms to human epidemiology and timed feeding patterns. J Neurochem 157(1), 53-72.
6. Qian J, Morris CJ, Caputo R et al. (2019) Sex differences in the circadian misalignment effects on energy regulation. PSNA 116(47).
7. Chaput JP, McHill AW, Cox RC et al. (2022) The role of insufficient sleep and circadian misalignment in obesity. Nature Rev Endocrin.
8. Gallegos JV, Boege HL, Zuraikat FM (2021) Does sex influence the effects of experimental sleep curtailment and circadian misalignment on regulation of appetite? Curr Op Endocr Metab Res 17, pp. 20-25.
9. Qian J, Morris CJ, Caputo R et al. (2019) Ghrelin is impacted by the endogenous circadian system and by circadian misalignment in humans. Int J Obesity 43, pp. 1644-1649.
10.  Leung GK, Huggins CE, Ware RS (2020) Time of day difference in postprandial glucose and insulin responses: Systematic review and meta-analysis of acute postprandial studies. Chronobiol Int 37(3), 311-326.
11.  Al-Naimi S, Hampton SM, Richard, P et al. (2004) Postprandial metabolic profiles following meals and snacks eaten during simulated night and day shift work. Choronobiol Int 21(6), 937-947.
12.  Crispim CA, Zimberg IZ, Gomes des Reis B et al. (2011) Relationship between Food Intake and Sleep Pattern in Healthy Individuals. J Clin Sleep Med 7(6).
13.  Clayton DJ, Mode, WG, Slater T (2020) Optimising intermittent fasting: Evaluating the behavioural and metabolic effects of extended morning and evening fasting. Nutr Bull 45(4), pp. 444-455.
14.  Farías R, Sepúlveda A, Chamorro R (2020) Impact of Shift Work on the Eating Pattern, Physical Activity and Daytime Sleepiness Among Chilean Healthcare Workers. Safety Health Work 11(3), pp. 367-371.
15.  Cain SW, Filtness AJ, Phillips CL et al. 2015) Enhanced preference for high-fat foods following a simulated night shift. Scan J Work Env Health 41(3), pp. 288-293.