How to Reset Your Circadian Rhythm in 7 Days

To reset your circadian rhythm, pick one wake-up time and keep it every day, weekends included. Get natural light soon after waking, eat your meals at regular times, and dim screens at night. Do this for seven days, then protect the new schedule so your internal clock has a steady target.

Your circadian rhythm is an internal clock that runs on a roughly 24-hour cycle, governed by the suprachiasmatic nucleus in the hypothalamus. According to the National Institute of General Medical Sciences (NIGMS), it influences sleep, hormone release, appetite, digestion and body temperature, and light and dark have the biggest influence on it.

When this clock drifts out of alignment (from jet lag, shift work, or inconsistent sleep habits), you can end up tired, unfocused, and unable to fall asleep at a reasonable hour. Over the long term, NIGMS notes that sleep loss and constantly shifting rhythms can raise the risk of obesity, diabetes, mood disorders and heart problems.

You cannot fall asleep at your target bedtime despite feeling tired. You wake up groggy even after seven or eight hours. Energy crashes hit at unpredictable times during the day.

Your weekend sleep schedule runs much later than your weekday one. Sleep scientists call that gap social jet lag, and a 2012 study in Current Biology estimated that about two-thirds of people in Western societies live with a significant amount of it.

Days 1 to 3: pick one wake-up time and keep it every day from now on. Get natural light within 30 minutes of waking, and dim screens two hours before bed, in line with Harvard Health's advice to avoid bright screens for two to three hours before sleep. Days 4 and 5: eat at the same times each day, with your first meal within an hour of waking and your last at least three hours before sleep, and cut caffeine after 2 p.m. In a 2013 study in the Journal of Clinical Sleep Medicine, caffeine taken six hours before bed still cut sleep by more than an hour.

Days 6 and 7: lock in your new wake time with Kairo’s alarm, which you turn off by completing a short mission, so sleeping through gets a lot harder. Your body can learn to expect that time: in a 1999 study in Nature, people who knew when they would be woken showed a rise in the hormone ACTH about an hour before their planned wake-up time.

Protect the first hour of your day from disruption. Avoid bright artificial light after sunset wherever possible. Weekend consistency is non-negotiable: in a 2008 study in Sleep and Biological Rhythms, waking about three hours later on the weekend delayed people's body clocks by around 40 minutes and left them sleepier on Monday and Tuesday.

During the first 30 days, your friends see you prove your wake-up every morning in Kairo, and the timeline shows your whole history with the habit, day by day. After that, keep going: in a 2010 study from University College London, new daily habits took a median of 66 days to feel automatic.