The emergency department is open 24/7, meaning that most ED physicians experience shift work. Shift work means that service is provided around the clock, whether it be night or day. Though shift work is almost always part of the job description for an ED doctor, it may not always favour the wellbeing of the physician. Inspired by a classmate, who adopted the sleep cycle of an ED early on in his M1 year, I wanted to discuss the science of sleep, the impact of shift work and how can we improve sleep hygiene when shift work is part of our job.
Basic Science of Sleep?
Sleep is part of every human being’s existence, as we could not live without it. Even though we have limited recollection of what happens during sleep, the process is quite complex. First, sleep latency is the time needed to fall asleep. Second, sleep is broken down into four stages that we oscillate through 4-5 times a night. The time it takes to go through all stages in a sleep cycle is approximately 90-120 minutes. The four stages we must pass through are called stage 1, stage 2, stage 3 and rapid eye movement (REM) sleep, respectively. Stage 1 through 3 is collectively called non-rapid eye movement sleep (NREM).
Stage 1 is the lightest stage of sleep and the first one we enter from wakefulness and is characterized by theta waves (4-7 Hz) on an EEG. Stage 2 is a deeper sleep and the period where we spend most of our time sleeping. It is characterized by theta waves, sleep spindles and k-complexes. Finally, stage 3 is known as slow-wave sleep, where delta waves predominate the EEG (0-4 Hz). Finally, after the three NREM stages, we enter REM sleep. REM is the deepest stage of sleep, despite the EEG activity being the closest to waking state. It is during REM sleep that we experience vivid dreams and have low muscle tone.
So why is sleep important?
First, there is a growing body of evidence that slow-wave sleep is when we store memories. Therefore, through proper sleep, we can consolidate memories, increasing retention of what we had learned the previous day. Moreover, sleep is important in our ability to regulate our emotions and respond appropriately to different circumstances. In addition, when we get proper sleep, we are more like to be in a positive mood, which can impact our patient interactions. Furthermore, sleep is important in immune regulation and the ability to fight off infection. Finally, sleep helps with muscle recovery and favours protein anabolism (growth). I personally believe that muscle recovery is important given the time spent on one’s feet during an ER shift. This theory of sleep and muscle recovery has been supported in sports medicine literature, and I am intrigued to see if this evidence also existed for ED Physicians and other medical specialities that are more physically demanding.
Shift work in health care workers
So, what happens when we don’t sleep? First, shift work and lack of proper sleep increase levels of fatigue and errors made by health care workers. This can have profound implications on patients, especially in the ED, where the severity of presentation is often greater than in other clinical environments. This is also alarming, given that shift workers tend to have a reduced total amount of sleep. This reduced amount of sleep most commonly impacts stage 2 NREM sleep and REM sleep, thus reducing the quality of sleep, in addition to the duration of sleep. This reduced sleep quality is worse in shift workers on a rotating shift schedule, compared to a nighttime or daytime only worker.
Moreover, in some studies of ER workers, the duration of sleep, especially REM, is less during the day then at night. So even if one believes they are still getting sleep, it may be of reduced quality. Some explanations for this diminished REM sleep during the day is the body’s natural response to a light-dark schedule and the release of melatonin, the sleep hormone. Melatonin is the sleep hormone, which often rises at nighttime when it is time to go to bed. Sunlight inhibits the release of melatonin, signalling our bodies that it is time to be awake. So, even if one tries to sleep in a dark room, the walk home from a shift or exposure to hospital lights may confuse the circadian clock, diminishing sleep quality. Finally, other studies have reported that shiftwork could increase cardiovascular disease risk, blood pressure, increase levels of stress and cause gastrointestinal issues. In women, shiftwork can cause fertility problems, such as premature birth and low-birth-weight infants.
How to combat some of the negative effects of shiftwork
There are many things we can do to manage our sleep quality and scheduling. For example, our sleep environment can be adjusted to maximize our sleep quality. Strategies can include the use of earplugs and ensuring a dark room devoid of as much light as possible. Additionally, sunglasses can be worn to and from a night shift, to avoid daylight, which may signal to our body the biological start or end of a day.
While some of the individual strategies may be useful to improve sleep hygiene with a shift work schedule, I also believe that some strategies should be implemented at the institutional level. For example, there is a body of literature which discusses that shifts longer than 12 hours are the most detrimental to sleep quality and a physician’s health. Moreover, the duration and timing of a break during a shift could help reduce some of the symptoms of shift work. Longer breaks during a shift are favoured, though the reasons why the longer breaks are better for sleep hygiene are unknown. Finally, scheduling strategies should be implemented. A paper by Burgess, has suggested that shifts be organized in a clockwise manner. For example, on performs a morning shift, then evening shift and a night shift etc. Moreover, morning shifts should not start earlier than 8:00 A.M. to favour our natural circadian rhythm. Issues with this approach are that multiple physicians work in an emergency department, many with families and different lives, which may prefer different schedules. Another issue is when a physician is sick, and another substitutes in. This could throw off the sleep schedule of both the physician cancelling and substituting the shift. Furthermore, is there an ideal number of days between shifts? Should this change with physician age knowing how melatonin levels decrease and the body becomes less resistant to stressors with ageing. While there are currently no gold standards with sleep regulation and shiftwork, we should at least be aware of why this is important and be mindful of our practices. It is easy to neglect our health in favour of our careers, something I have been all too familiar with and hope to improve.
I would like to end this article with a few comments about sleep. While the published literature may not tell a complete story due to the publication bias, there are a few things we can take away. Sleep is essential for our health and mental wellbeing. Shiftwork cannot be avoided, and, if self-care is not practiced, lack of sleep can have detrimental effects on our body and wellbeing. The impact of shiftwork on everyone can be different. Therefore, individual strategies to advocate for personal health is important. Organizations have a role in fostering an environment that supports good sleep habits and employee health. Finally, medical schools and residency programs should incorporate time to educate students on sleep hygiene and hopefully, inspire students to be agents of change in their own hospitals, thus fostering wellness practices. I look forward to joining you next time while I talk about imposter syndrome in medicine.
References and Further Reading
- Burgess P. A. (2007). Optimal shift duration and sequence: recommended approach for short-term emergency response activations for public health and emergency management. American journal of public health, 97 Suppl 1(Suppl 1), S88–S92. https://doi.org/10.2105/AJPH.2005.078782
- Dall’Ora C, Ball J, Recio-Saucedo A, Griffiths P. Characteristics of shift work and their impact on employee performance and wellbeing: A literature review. Int J Nurs Stud. 2016;57:12-27. doi:10.1016/j.ijnurstu.2016.01.007
- Dattilo M, Antunes HK, Medeiros A, et al. Sleep and muscle recovery: endocrinological and molecular basis for a new and promising hypothesis. Med Hypotheses. 2011;77(2):220-222. doi:10.1016/j.mehy.2011.04.017
- Gruber R, Cassoff J. The interplay between sleep and emotion regulation: conceptual framework empirical evidence and future directions. Curr Psychiatry Rep. 2014;16(11):500. doi:10.1007/s11920-014-0500-x
- Halson SL, Juliff LE. Sleep, sport, and the brain. Prog Brain Res. 2017;234:13-31. doi:10.1016/bs.pbr.2017.06.006
- Ibarra-Coronado EG, Pantaleón-Martínez AM, Velazquéz-Moctezuma J, et al. The Bidirectional Relationship between Sleep and Immunity against Infections. J Immunol Res. 2015;2015:678164. doi:10.1155/2015/678164
- Kuhn G. Circadian rhythm, shift work, and emergency medicine. Ann Emerg Med. 2001;37(1):88-98. doi:10.1067/mem.2001.111571
- Marshall L, Helgadóttir H, Mölle M, Born J. Boosting slow oscillations during sleep potentiates memory. Nature. 2006;444(7119):610-613. doi:10.1038/nature05278
- Paller KA, Voss JL. Memory reactivation and consolidation during sleep. Learn Mem. 2004;11(6):664-670. doi:10.1101/lm.75704
- Qureshi, S., Karrila, S., & Vanichayobon, S. (2018). Human sleep scoring based on K-Nearest Neighbors. Turkish Journal of Electrical Engineering & Computer Sciences, 26(6), 2802-2818.
- Sack RL, Lewy AJ, Erb DL, Vollmer WM, Singer CM. Human melatonin production decreases with age. J Pineal Res. 1986;3(4):379-88. doi: 10.1111/j.1600-079x.1986.tb00760.x. PMID: 3783419.