How Shift Work Affects Your Sleep Cycles

If you work shifts, you already know how tough it can be to stay awake when the rest of the world is winding down—or to fall asleep when everyone else is starting their day. Your body naturally follows a built-in sleep-wake cycle, but shift work throws that rhythm off, making it harder to get the rest you need.

What Counts as Shift Work?

Shift work refers to any work schedule that falls outside the typical 7:00 a.m. to 6:00 p.m. window. It includes:

• Afternoon or evening shifts (e.g., 3:00 p.m. – 11:00 p.m. or 4:00 p.m. – midnight)

• Overnight shifts (e.g., 11:00 p.m. – 7:00 a.m. or midnight – 8:00 a.m.)

• Rotating shifts, where schedules change from week to week or even day to day

• Split shifts, with long breaks in between work periods

• Compressed workweeks, with longer shifts condensed into fewer days

How does shift work impact your sleep cycle?

Our bodies are programmed to follow a 24-hour sleep-wake cycle, controlled by the circadian clock, an internal system in the brain that regulates when we feel awake and when we feel sleepy. This clock is heavily influenced by natural light—when the sun rises, our bodies expect us to be up and active, and when it sets, they prepare us for sleep.

But when you're working shifts, your sleep-wake cycle is also shifted by about 9-12 hours, but the sun doesn’t shift with you. Instead, it continues to rise and set at its usual time. Your circadian clock uses the sun, in part, to regulate your sleep-wake cycles and it doesn’t know that you’ve shifted your work schedule.

Unlike traveling to a different time zone—where your body slowly adjusts to a new schedule—shift work creates an ongoing conflict. Your body still expects you to sleep at night, even if your job demands otherwise. This misalignment can lead to sleep deprivation, reduced alertness, and even long-term health effects.

Can Your Body Adjust to Shift Work?

Yes, but it takes time. When people travel across time zones, their circadian clocks can shift by about 1-2 hours per day, meaning it may take up to 12 days to fully adjust to a 12-hour difference. For shift workers, frequent schedule changes can make full adaptation tricky, but finding small ways to support your sleep-wake cycle can help improve rest and alertness over time.

Finding a Sleep-Wake Routine That Works for You

Shift work affects not just your sleep but also your energy levels, mood, and even your family and social life. That’s why it’s important to develop a sleep-wake routine that fits your specific work schedule. Whether you’re on permanent nights, rotating shifts, or split shifts, small adjustments can make a big difference in how well you rest and function. This might mean setting up a dedicated sleep space, planning meals that support your energy levels, or coordinating with loved ones so you can still spend quality time together.

By understanding how shift work impacts your body and using the right strategies, you can improve your sleep, stay more alert, and better manage the challenges of an unconventional schedule.