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How Shift Work Affects the Circadian Rhythm

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Have you ever tried waking up in the middle of the night to start your day? Even if you’ve spent the entire day asleep, your body will try to convince you that you should stay in bed and go back to sleep. It is nighttime after all.

Night shift work is often referred to as the “graveyard shift.” An old legend has it that the term came from graveyard workers who were on the lookout for instances where they had accidentally put a person in a coffin who was still alive.

This story has been debunked; it’s called the graveyard shift because the nighttime working hours are often referred to as being as quiet as a graveyard.

We think there’s an even more compelling reason to call it the graveyard shift, though. If you’re not careful, it could put you in an early grave. Sound dramatic? When you see how this type of work can be potentially harmful to your health, you may look into swapping schedules or at least taking to heart some of our tips to make it less of a strain on your health.

Note: any work that employees do outside the standard nine-to-five grind is technically considered shift work, but for this article, we’ll focus on how night shift work affects the circadian rhythm.

How Night Shift Work Affects Our Sleep

Night shift work wreaks havoc on our circadian rhythm. A circadian system is a biological process that works in cycles of 24 hours. It’s like our body’s internal clock. Its most potent signal is light and darkness, so it tells us to be awake and alert during the day and drowsy or asleep at night. Internally, it’s also creating different hormones and chemicals responsible for body temperature, appetite, and even digestion.

When people work these hours, they turn the natural rhythm on its head, and instead of sleeping at night, they now have to stay awake during this time. Conversely, most people naturally wake up and feel alert when the sun comes up. However, when subjected to this work schedule, they must make a more concerted effort to fall asleep and stay asleep.

People who maintain this schedule may end up with something called “shift-work sleep disorder.” Two main symptoms are insomnia and excessive daytime sleepiness (EDS).

Effects of Disrupted Circadian Rhythm


When people willfully ignore these signals by remaining awake when it’s dark and trying to sleep during the day, one of the most pronounced effects is fatigue. They are battling daily with the circadian rhythm that’s telling them to do the opposite of what they’re doing. When they’re trying to perform nightly duties, they’ll struggle to stay awake. And when the night is over and it’s time for bed, it may be more difficult to fall asleep.

Our bodies can adjust to our new schedule with discipline and consistency, but the threat of fatigue is always on the horizon.

Sleep Disorders

Because shift workers are battling their internal clock, they’re likely to experience both insomnia and excessive daytime drowsiness. The difficulty in falling asleep occurs because they’re often trying to sleep when it’s daylight, and the rest of the world is active. At night, drowsiness is common because the body’s clock is signaling that it’s time for bed.

Mood Problems

Fatigue and sleep deprivation are prime ingredients for mood problems. This issue is also exacerbated by the fact that hormones are thrown off balance when the circadian clock is out of sync.

Decreased Cognitive Abilities

Subjects on a modified work schedule tested for cognitive abilities scored significantly lower than those on a standard schedule. The effect is most pronounced on those who are middle-aged, indicating that the older we get, the more difficult it is to adapt to a modified schedule.

Poor Reflexes

Reaction times slow when people are drowsy. The effect of fatigue is poorer reflexes as the brain’s abilities are dulled.

Weak Immune System

The circadian rhythm isn’t just responsible for making us feel awake or drowsy. It also sends powerful immune system signals. When the clock is off, so are those signals. This makes people more susceptible to colds, the flu, and even chronic diseases and health conditions.

Poor Decision Making

Sleep deprivation is also associated with poor decision-making abilities. This is partly due to fatigue and the inability to think clearly. It can also be blamed on the brain’s chemical makeup when it doesn’t get the rest it needs.

Even just one night of a thrown-off pattern can rewire the brain and make its fight-or-flight response more active. When you’re in fight-or-flight as opposed to a calm, serene state, your chances of making a logical and rational decision decrease.

What is Graveyard Shift Work Disorder?

Graveyard shift work disorder is caused by a work or sleep-wake schedule that is outside the “normal” hours. If someone is waking up in the middle of the night to go to work or start their day, they are susceptible to this condition.

The nature of this disorder entails having a schedule that necessitates sleeping in the daytime and staying awake at night. This defies the body’s natural internal clock, which is set to a 24-hour circadian rhythm. When this body clock is thrown off, the two most immediate effects are insomnia when it’s time for sleep and day-time drowsiness when it’s time to be awake.

Nearly 20% of Americans are at risk for this disorder, including emergency medical doctors, firefighters, police officers, truck drivers, military personnel, and more.

How it Affects our Health


Stress is both chemical and situational. The off-balance hormones are one side effect, but there’s also a psychological component. Not being on the same schedule as everyone else can make it feel like you’re missing out on time with friends and family. Also, the “graveyard shift” is a quiet time. For those who spend this time awake while the world is sleeping, it can feel very isolated.

Health Problems

Shift work disorder has been linked to a variety of diseases, even cancer. The most common health problems observed in people on this schedule include insulin resistance, metabolic syndrome, and heart disease. Basically, these workers face a higher risk of diabetes and being overweight.


Seven percent of fatal car accidents are caused by sleeping or drowsiness at the wheel. And, it’s estimated that other fatalities blamed on speeding and collisions are also directly influenced by fatigue.

Drowsy Driving Survey

Drowsy Driving
How often do you zone out while driving?
Have you ever been in, witnessed, or known someone who has gotten into an accident that was a result of drowsy driving?
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Trouble Concentrating

One notable symptom of shift work disorder is impaired mental abilities and difficulty concentrating. Being drowsy or fatigued is one cause, along with a brain that’s struggling to adapt to an irregular schedule.

Poor Job Performance

Absenteeism and mistakes are higher among shift workers than it is for those on a traditional schedule. We also discussed that the ability to exercise sound judgment is impaired, which also hinders job performance.

Sleeping Tips for Night Workers

Avoid Working a Number of Night Shifts in a Row

WebMD recommends avoiding working too many consecutive night shifts, but your best bet may be to adjust to a schedule rather than constantly make the body adapt to a new plan.

Rush University developed a system to help workers adjust to a nighttime work schedule, and after the brief adjustment period, their bodies showed none of the impairments that typically come with the hazards of working the graveyard shift.

Avoid Frequent Rotating Shifts

One of the worst things you can do for your body is to rotate between day and night working hours. Most employers are aware of the dangers of subjecting their staff to this type of schedule. Still, if you have multiple jobs, you’re paying your dues in a high-stress environment like a hospital or police station, or are on parental duties, schedule rotations may be unavoidable.

If that’s the case, try following the rest of the tips to help offset the effects of an erratic schedule.

Avoid Long Commutes

If you’re already sleep-deprived, a long commute robs you of precious shuteye. Also, sleep-deprived workers are more prone to have car accidents, so it’s logical to minimize car time.

Keep Your Workplace Lighted

Just because it’s dark outside doesn’t mean you have to work in the dark. By keeping your workplace well-lit, you can help offset some of the effects of the body’s internal clock signaling that it’s time for sleep.

Limit Caffeine

Caffeine may be necessary at times to get through a night, but it should be avoided whenever possible. Artificially stimulating your system in the middle of the night could make it more challenging to fall asleep at the end of a shift and create a perpetual cycle of insomnia.

Find Out More: Caffeine Effects on Sleep

Avoid Bright Lights on Your Way Home

Now that your “work day” is over, it’s time to wind down for the day and get some sleep. Therefore, it’s best to avoid bright lights on your way home. This may be impossible if you’re taking public transport or your shift ends when the sun is out, so opt for dark sunglasses and avoid running errands.

Stick to a Regular Sleep-Wake Schedule

Even on your days off, try to keep a schedule that’s consistent with your work schedule. It doesn’t have to be exact, and you can actually enjoy social activities. Our recommendation is to stay up as late as possible on your days off and then sleep in until close to noon. For example, if you sleep from 3 AM until about 11 AM, you’re still relatively close to your graveyard schedule, but you can still spend time with friends and family.

Limit Phone Calls and Visitors

Tell friends and family when you plan on sleeping and ask them to refrain from contacting you during those hours. If you’re jarred awake in the middle of the day, it can be harder to fall back asleep.

Use Blackout Blinds or Heavy Curtains

Create an environment of total darkness even if it’s daylight by putting blackout curtains in your bedroom. You’ll simulate a cave-like atmosphere that makes it easier to doze off and stay asleep.

Frequently Asked Questions

Are there psychological effects of working on a graveyard shift?

Yes, and they’re often overlooked. Working the graveyard shift is a lonely existence. Your friends and family members are usually asleep. When it’s time for you to go to bed, they’re often out enjoying fun activities. It leads to feelings of isolation and depression. While this is a challenge, do your best to adjust your schedule on your off days so you can still spend time with the people you care about.

How can a shift work disorder be treated?

The first course of action is to follow the tips listed in this article. By practicing proper sleep hygiene, you can go a long way toward treating this disorder and living a relatively normal life despite having a different schedule.

In some cases, medications may be prescribed to either help keep you alert or allow you to fall asleep more easily. Doctors are also known to offer antidepressants for mood and sleep, though the best course of action is often a more natural approach.

How to survive a night shift with no sleep?

If you’re struggling to stay awake during the night shift, here are a few tips to help you survive:

  1. Try a powernap during your “lunch” break. Limit it to 20 minutes, or you may end up in a deep sleep and feel groggy the rest of the night.

  2. Eat small portions. Eating helps keep you awake, but don’t overdo it, or your waistline will suffer.

  3. Move around. Get up at regular intervals and walk around. Sitting still for too long will make you drowsy.

  4. Talk it out. Chat with coworkers. If you’re by yourself, turn on a radio, podcast or television and feel free to add your own commentary. It’s not as crazy as it sounds.


While it might seem like you’re all alone with a schedule that makes living a normal life seem impossible, remember that nearly 20% of the population is in a similar situation. You may have to work a little bit harder to maintain a healthy schedule, but with careful planning, it is manageable.

Sources and References:

  1. Sleep Loss and Fatigue in Shift Work and Shift Work Disorder –

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Jill Zwarensteyn

Jill Zwarensteyn


About Author

Jill Zwarensteyn is the Editor for Sleep Advisor and a Certified Sleep Science Coach. She is enthusiastic about providing helpful and engaging information on all things sleep and wellness.

Combination Sleeper