Some form of shift work, whether during the day or night, is performed by about 20% of the American workforce.
Most sleep experts conclude that working at night isn’t biologically natural: humans evolved to sleep at night and be active during the day, and many cellular processes follow a circadian rhythm.
For some people it’s easy to change their sleep–wake schedule; others find it very difficult to sleep during the day and remain tired at work. This difficulty is known as shift work disorder.
Although there is not yet conclusive data on how many shift workers have shift work disorder, research shows several consequences of shift work — traffic and workplace accidents, gastrointestinal illness, heart disease, and psychiatric disorders. For workplace risk planning and related information, see Workplace Challenges and Insurance Solutions.
Cancer, for example, may be linked to shift work through melatonin suppression; melatonin is a naturally occurring hormone and antioxidant that is secreted most during nighttime sleep, so working at night under bright lights can reduce melatonin production.
Heart disease is another well-researched consequence; some studies suggest people who sleep during the day have higher blood pressure during sleeping hours.
Cortical rhythm (stress response) and leptin levels (which help signal fullness) are also altered by daytime sleeping. Some research shows that glucose and insulin can rise and prediabetes can develop within days of shifting sleep to daytime hours.
Shift work was classified by the International Agency for Research on Cancer as a probable carcinogen.
Some people wonder whether night owls or those naturally inclined to stay up late are less affected; this is still being studied, so there is no clear answer yet. Meanwhile, there are practical steps anyone doing shift work can use to help minimize fatigue and insomnia.
Tips for shift workers
- Use light to your advantage while you’re working, since light signals the brain that it’s time to be awake and alert. On your drive home, wear sunglasses or blue–light–filtering lenses and a brimmed hat to limit daylight exposure and begin signaling that it’s time to sleep.
- Make your daytime sleep environment sleep-friendly: install blackout shades, turn the ringer off the phone, and disconnect the doorbell. Make sure household members understand that daytime sleep is your bedtime.
- Try not to alter your work sleep–wake schedule too much on days off. Allow daylight hours for social activities and errands, but avoid large, sudden shifts in sleep timing when possible.
- If environment and behavior changes don’t work, consider short-term melatonin; some studies show it can help those trying to sleep during the day. Take melatonin close to the time you plan to sleep, since it generally begins working within about 30 minutes.
- Most people find help through environment and behavior changes. For those not helped by these measures, armodafinil (Nuvigil) is a prescription medication approved for shift work disorder and sometimes used to improve wakefulness.
For more background on shift work and its broader effects, see Understanding Shift Work and Its Impacts.
Frequently Asked Questions
What is shift work disorder?
Shift work disorder is a circadian rhythm sleep disorder where a person has excessive sleepiness or insomnia tied to a work schedule that overlaps typical sleep time.
Can melatonin help me sleep during the day?
Melatonin can help some people fall asleep during the day, but it should be timed close to the desired sleep time and discussed with a clinician if you have ongoing problems.
Does shift work increase long-term health risks?
Research links shift work to higher risks of cardiovascular issues, metabolic changes, and possibly cancer, though individual risk varies with schedule, light exposure, and behavior.
What practical steps reduce fatigue for night shift workers?
Recommendations include controlling light exposure, creating a dark, quiet daytime sleep environment, keeping a consistent schedule, and seeking medical advice if sleep problems persist.