Determine your temperature minimum, which is the point in your 24-hour cycle when your body temperature is lowest, typically 90 minutes to two hours before your average waking time. This is a critical reference point for understanding and shifting your circadian clock.
To shift your circadian clock to wake and sleep earlier (phase advance), expose your eyes to bright light, exercise, and/or eat in the four hours after your temperature minimum. This strategy can shift your clock by 1-3 hours per day.
To shift your circadian clock to wake and sleep later (phase delay), view bright light, exercise, and/or eat in the four to six hours before your temperature minimum. This approach can also shift your clock by 1-3 hours per day.
Get as much light, ideally sunlight, into your eyes during the period you want to be awake and alert. Aim for at least 100,000 lux before 9-10 a.m. (assuming a 5-8 a.m. wake-up) by going outside, even on cloudy days, or using artificial lights if sunlight is insufficient.
Get as little light into your eyes when you want to be asleep or drowsy. Crucially, avoid bright light and even not-so-bright light between 10-11 p.m. and 4 a.m. to prevent unwanted clock shifts.
Look at sunlight around the time the sun is setting to adjust down the sensitivity of your eyes, which helps prepare your system for a good night’s sleep.
For eastward travel (e.g., California to Europe), 2-3 days before your trip, start getting up earlier (e.g., 5:30 a.m.) and expose yourself to bright artificial light, exercise, and/or eat a meal. This helps advance your clock before arrival.
For westward travel (e.g., New York to California), use stimulants like caffeine, exercise, and/or sunlight (or artificial light if no sun) in the late afternoon/evening (e.g., 6-8 p.m.) to help you stay up later and delay your clock to the local schedule.
When traveling or adjusting to a new schedule, eat your meals according to the local schedule for alertness to help entrain your internal rhythms effectively.
When adjusting to a new time zone, avoid taking naps that extend beyond a short duration (e.g., 20 minutes to an hour), as longer naps can disrupt your ability to fall asleep on the local schedule later.
Wear red lens glasses in the evening after the sun goes down to filter out short-wavelength light from screens and LED lights. This prevents melatonin suppression and improves your transition to sleep.
If you are a shift worker, aim to stay on the same schedule for at least 14 days, including weekends, to maintain circadian rhythm stability and minimize negative health effects.
Even if you are not a shift worker, avoid sleeping in significantly on weekends to prevent disrupting your circadian rhythm, which can lead to a form of social jet lag.
During your work shift, especially if it’s at night, see as much light as you safely can during the phase of your day when you need to be awake and alert to support your circadian rhythm.
As a general rule for circadian alignment, if your body temperature is decreasing, avoid light; if your body temperature is increasing, seek light to support your natural sleep-wake cycle.
When sleep-deprived (e.g., new parents, caregivers) or struggling to fall back asleep, use Non-Sleep Deep Rest (NSDR) protocols to recover, maintain autonomic regulation, and teach your nervous system to turn off thoughts and go to sleep.
To shift your clock, take a hot shower to induce a subsequent cooling effect, which will delay your clock. Alternatively, use a cold shower or ice bath to induce a thermogenic effect, which will increase your body temperature and advance your clock.
For trips lasting 72 hours (3 days) or less, try to stay on your home schedule as much as possible to avoid significant jet lag and the need for clock adjustment upon return.
Melatonin can induce sleepiness and help you fall asleep in a new location, but it does not help you stay asleep and has endocrine effects. Behavioral protocols involving light, exercise, and temperature are generally preferred for clock shifting, but consult a doctor if considering melatonin.