Your circadian rhythm plays a huge role in when you feel tired and awake. It controls when stimulating hormones like cortisol and relaxing ones like melatonin are released throughout the day. The circadian rhythm is heavily affected by light, which is why we find it difficult to fall asleep when traveling to a new time zone or working night shifts.
A healthy circadian rhythm will reset every 24 hours or so, but everybody's is a little different. This is part of the reason some people are naturally night owls, while others prefer to wake up early in the morning. If you want to improve your sleep, working with your natural circadian rhythm is key. And that means keeping your sleep-wake schedule as regular as possible.
"Getting up at the same time every day is sort of like the superhero of sleep advice. It reinforces your natural circadian rhythm," Robin MacFarlane, Ph.D., a clinical psychologist and sleep specialist, says. "It may not always feel good to get up at the same time every day, but over the long run, it's going to leave you feeling as refreshed as you can be."
Ideally, your wake-up time shouldn't change by more than an hour on any given day—yes, even on the weekends!