Some evidence for working night shifts

Night shifts

Night shifts – love them or hate them – are an inescapable part of emergency medicine. Personally, I have always loved the atmosphere of a hospital after hours. Although I am apparently weaker than many of my emergency colleagues, in that I find myself utterly destroyed after a night shift, I do enjoy the medicine that a night shift brings. This post will briefly review 10 evidence based measures to improve night shifts, based on an excellent paper by the incredible Jordana Haber (@JordanaHaber) and Patrick Wallace.

The Paper

Wallace PJ, Haber JJ. Top 10 evidence-based countermeasures for night shift workers. Emerg Med J. 2020 Sep;37(9):562-564. doi: 10.1136/emermed-2019-209134. PMID: 32332056

#1 Schedule for circadian rhythm

I found that poorly staggered shifts were a big problem early in my career, but the rise of automated scheduling software seems to have improved the issue. It is much easier to delay bedtime by a few hours than it is to force yourself to get up a few hours earlier. For that reason, it is better to start a run of shifts earlier in the day and transition to later shifts. Working an afternoon shift one day and then a morning shift the next not only results in a shorter turnaround time, but is also more disruptive to circadian rhythms. Other suggestions are to schedule fewer transitions (work all days this week and all afternoons next week, rather than a mix) and make transitions between shifts smaller (6 hours or fewer). These practices are associated with higher levels of satisfaction, better performance, and improved alertness.

There are many strong opinions about how night shifts should be scheduled. Sleep debt accumulates over consecutive night shifts and therefore these authors suggest limiting the number of consecutive night shifts to 2 or 3. However, they also suggest avoiding single night shifts because of the significant disruption to circadian rhythms. Night shifts longer than 8 hours have been associated with increased medical errors, so they also suggest an 8 hour cap, and that shifts should not extend beyond their scheduled end time.

#2 Nap before your shift

This one is pretty self explanatory, and the one habit that most ED docs figure out for themselves. There are multiple studies that demonstrate reduced fatigue, increased alertness, and perhaps improved performance with napping. They suggest the ideal time is between 14:00 and 16:00, but that the timing is less important than just getting a nap in.

#3 Maximize bright light on shift

This seems to be a constant struggle. There is always someone who wants to have all the lights off at night, but bright light is important in keeping people alert. (And emergency medicine requires alertness.) This ties into the circadian rhythms, as bright light (and especially blue light) is the signal to the body that you are supposed to be awake. The authors suggest that providers advocate for their departments to install high intensity blue wavelength lights for night shifts.

#4 Nap on shift, if you can

Not surprisingly, one of the best solutions to sleep deprivation is sleep. There are studies that suggest napping on shift improves performance, mental agility, and decreases sleep debt. However, the length of nap is important, because naps longer than 15 minutes are associated with sleep inertia – a sensation of significant grogginess lasting about 30 minutes after waking. Napping earlier in the shift, before the 3-4 am circadian nadir, can also help prevent sleep inertia. Of course, in many places, napping is simply impractical, but based on the benefits, it may be worth adjusting schedules such that naps are possible.

#5 Caffeine is amazing (but drink it early in the shift)

Caffeine is every shift worker’s drug of choice. It improves performance, alertness, and cognitive function. Their suggested dose is 4 mg/kg – and I am considering gaining weight just so I can drink an extra coffee a day. They suggest drinking a caffeinated beverage between 12:20 and 1:20 am, but it is very important to avoid caffeine within the last 4 hours of your shift, so that sleep is possible when you get home.

#6 Avoid large meals

With the large volume of coffee in my stomach and the number of patients waiting to be seen, I have never really considered eating a large meal while on shift. Luckily, that fits with these authors’ suggestion of avoiding large meals, as they can lead to delayed response time, cognitive impairment, and increased errors. Instead focus on smaller snacks. Similarly, fats and proteins are associated with less sleepiness than carbohydrates.

#7 Minimize light exposure on the commute home

Bright light keeps you awake. That’s why we need bright lights on in the department overnight. However, once your shift is over, you want to limit your exposure to bright light so that you will be able to sleep when you get home. Dark sunglasses or sunglasses specifically designed to block blue light are recommended. If you don’t have to drive, they even recommend welder glasses to really decrease the amount of light exposure. 

#8 Consider melatonin

Not based on as good science as the other recommendations, melatonin has a relatively good safety profile and there is a potential benefit. A Cochrane review suggests that melatonin increased the length of daytime sleep by a mean of 24 minutes, which doesn’t sound like a lot, but considering how much one normally sleeps during a day, it could be significant.

#9 Sleep in a dark environment

I am a huge proponent of this recommendation. I have custom fitted black-out blinds made for each of my windows, so that not a single photon of light may enter from the outside world. Blackout curtains and sleep masks have been shown to improve sleep, recovery, mood, and performance. Your sleep environment matters – invest in it. (I would add a comment on the benefits of quiet, and investing in good sound-proofing and white noise machines.)

#10 Sleep in a cool environment

Again, your sleep environment is important. This recommendation is sometimes a little more contentious, as some people really prefer getting into a warm bed, but there is reasonable evidence to suggest that sleep is promoted by a cool environment. These authors suggest that it is the heat loss from peripheral vasodilation that helps, which can be aided by a warm water bottle near the feet, so maybe you can have your cake and eat it too. 

Bottom line

Looking after ourselves on night shifts is essential. It is essential because we will be doing these shifts throughout our careers, and our personal well being needs to be a priority. It is also essential for our patients, because we cannot not provide our patients with optimal care if we are not alert on shift. This article was a great summary of the available evidence, and therefore a worthwhile read for all nightshift workers. 

Image by Sammy-Williams from Pixabay

Cite this article as:
Morgenstern, J. Some evidence for working night shifts, First10EM, January 11, 2021. Available at:

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