Podcast 509: Circadian Rhythm and Shift Work, From Z to Z - The Emergency Medical Minute

Podcast 509: Circadian Rhythm and Shift Work, From Z to Z

Contributor: Jared Scott, MD

Educational Pearls:

  • Sleep deprivation and disturbed sleep cycles increases the risk of many acute and chronic medical issues such as motor vehicle accidents, diabetes, cardiovascular disease, psychiatric disease,  and shift work sleep disorder (difficulty sleeping, fatigue, interference with daily activities)
  • Stages of sleep 
    • Stage 1: 5-10 minutes (light sleep, may not recognize). 
    • Stage 2: Spindle waves, mostly unstudied 
    • Stage 3: Restorative sleep
    • Stage 4 (REM): Paralysis, memory consolidation
  • One sleep cycle takes about 120 minutes
  • Light is critical for regulating sleep cycles. Exposure to light (especially blue light) inhibits melatonin release from the pineal gland, which influences the suprachiasmatic nucleus (master sleep controller in the brain)
  • How can you optimize sleep before your night shifts? On the day of your first night shift, sleep until you wake naturally, then take a 90min nap between 2-6pm before you start your shift 
  • Sleepy on shift? A 5 minute nap is helpful to increase your attention span and thinking. A 30 minute nap is good for achieving more restorative sleep. Naps between 30 and 60 minutes are not recommended due to increased sleep inertia 
  • How do I optimize myself on shift? Keep active and take a 5 minute nap if needed. Do not use caffeine within the last 4 hours of your shift (it will interfere with your sleep!). More than 200-300mg a caffeine are not recommended, if you do use it.Use built in checks to reduce errors, as errors are increased during night shifts! 
  • Leaving your shift, reduce exposure to light by wearing sunglasses, avoid screens and alcohol, and get to sleep ASAP
  • Got things to do? Remember that some sleep is better than none! 


Kuhn G et al. Circadian rhythm, shift work, and emergency medicine. Ann Emerg Med. (2001) 37:1, 88-98.

McKenna Helen, Wilkes Matt. Optimising sleep for night shifts BMJ (2018). 360:j5637

Summarized by Will Dewispelaere, MS4 | Edited by Erik Verzemnieks, MD

Music credit: “Smooth Lovin” by Kevin MacLoed (incompetech.com). Licensed under Creative Commons By Attribution 3.0 License. http://creativecommons.org/licenses/by/3.0/

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