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Sleep schedule shifter: move your sleep earlier or later, one night at a time
Type in when you go to bed and wake up now, and when you want to. The planner moves bedtime and alarm together by a fixed step every night and lists each night with its date. The example below fixes a schedule that has slid four hours late, starting Monday, October 12.
Updated October 5, 2026 · Step sizes: Eastman & Burgess 2009, Sack et al. 2007 (AASM) · Light: Khalsa 2003 · Caffeine: Drake 2013
Your plan
Mon Oct 12
Your sleep has to move 4 hours earlier. Start on the night of Mon Oct 12 with lights out at 2:30 am and an alarm at 10:30 am, move 30 minutes earlier each night, and you arrive at 11:00 pm and 7:00 am on the night of Mon Oct 19 — 8 nights in all.
| Night of | Lights out | Alarm | Sleep | Last coffee | Move |
|---|---|---|---|---|---|
| Mon Oct 12 | Tue 2:30 am | Tue 10:30 am | 8 h | 8:30 pm | 30 min earlier than the night before |
| Tue Oct 13 | Wed 2:00 am | Wed 10:00 am | 8 h | 8:00 pm | 30 min earlier than the night before |
| Wed Oct 14 | Thu 1:30 am | Thu 9:30 am | 8 h | 7:30 pm | 30 min earlier than the night before |
| Thu Oct 15 | Fri 1:00 am | Fri 9:00 am | 8 h | 7:00 pm | 30 min earlier than the night before |
| Fri Oct 16 | Sat 12:30 am | Sat 8:30 am | 8 h | 6:30 pm | 30 min earlier than the night before |
| Sat Oct 17 | Sun 12:00 am | Sun 8:00 am | 8 h | 6:00 pm | 30 min earlier than the night before |
| Sun Oct 18 | Sun 11:30 pm | Mon 7:30 am | 8 h | 5:30 pm | 30 min earlier than the night before |
| Mon Oct 19 | Mon 11:00 pm | Tue 7:00 am | 8 h | 5:00 pm | on target from here — keep these times |
No email and no sign-up. The file is built in your browser from the table above; each night becomes a lights-out reminder 30 minutes ahead and a wake-up alarm.
- A bedtime after midnight is listed under the evening the night starts; the lights-out time itself falls on the next calendar day.
How fast the body clock moves, and why earlier is the slow direction
The first two figures are early estimates from real jet travelers, quoted in the Eastman and Burgess review. Nobody was lighting or darkening their day on purpose, and the clock still gave up more hours going later than going earlier. When the same authors write a travel plan with bright light placed at the right time, they assume an advance of 1.5 hours a day and a delay of 2 hours a day. Their advice for the sleep schedule itself is stricter: do not move it earlier by more than an hour a day.
A quick lab comparison in the AASM review shows why faster is not always better. Volunteers who advanced their sleep schedule by 2 hours a day, with morning bright light, moved a melatonin marker of the body clock by 1.8 hours over three treatment days. Those who advanced by 1 hour a day moved it by 1.5 hours. Doubling the schedule step bought 0.3 hours of clock, and the review calls the gap marginal.
This planner defaults to 30 minutes a night. That is far inside every figure above, so you should be able to hold it on a work week, and the arrival date is the one the plan prints for you.
You are moving earlier, the slower direction in the traveler estimates. The same distance in the other direction needs fewer nights, so give this plan its full count and do not skip a row to catch up.
You are moving later, the faster direction in the traveler estimates. The same distance in the other direction takes more nights, so a short plan here is realistic.
Light and caffeine, row by row
Light is the signal the body clock follows. In the phase-response study by Khalsa and colleagues, bright light in the biological evening pushed the clock later, and bright light in the biological morning pulled it earlier. So the two directions ask for opposite habits at the two ends of the day, and the table lists them side by side. The column for your direction is shaded.
Caffeine does not follow the direction. In a home study of 12 healthy sleepers, 400 mg of caffeine six hours before bedtime cost them more than an hour of sleep on the portable monitor. At six hours the sleepers' own diaries did not pick it up, which is why the last-coffee column counts back six hours from every lights-out time and is not left to how you feel.
| Moving earlier | Moving later | |
|---|---|---|
| Bright light | After the alarm, in the morning (7:00 am by the end of the plan), outdoors if you can | In the evening, before lights out (11:00 pm by the end of the plan) |
| Keep light low | In the evening and the last hour before lights out | Right after the alarm — sunglasses for the first walk outside |
| Last caffeine | 5:00 pm for a 11:00 pm lights out (6 hours before) | 5:00 pm for a 11:00 pm lights out (6 hours before) |
| Largest nightly step | 60 minutes (Eastman & Burgess) | 1 to 2 hours (AASM review) |
Times come from the "want" fields above · light direction: Khalsa et al. 2003 · caffeine: Drake et al. 2013 · step sizes: Eastman & Burgess 2009, Sack et al. 2007
Your plan crosses 4 h, so timing matters. For an 8-hour sleep that ends at your current alarm, the temperature low point falls at about 6:30 am to 8:00 am; at the end of the plan it falls at about 2:30 am to 4:00 am. Bright light after that low point pulls the clock earlier; bright light before it pushes the clock later. When you move earlier, that means the light you get after the alarm helps, and the light you get late in the evening works against you.
Why sleep times drift, and why drifting back is slow
Most self-made drift has the same shape. Weekday alarms hold the morning in place, free days let it slide, and a few late nights turn into a new schedule. Roenneberg and colleagues call the gap between the body clock and the social clock social jetlag, and they report that it leaves people short of sleep over time. If your bedtime has crept out three or four hours, the slide has probably been cheap and the way back is not.
The AASM review points in the same direction. It cites the view that delaying sleep times is easier than advancing them, which is why shift schedules that rotate forward are favored. A body clock that has settled late resists being pulled early, and an early alarm on its own does not do the pulling; the light you get after you wake does. Keep the alarm where the plan puts it every day, including weekends, and let the bedtime follow the evening's sleepiness inside the step.
If the drift is lifelong, or the schedule snaps back within days every time you move it, that is a pattern a clinician should look at. The AASM reviews delayed sleep phase as a condition of its own, and a plan on a web page does not replace that visit.
For a clock change the distance is one hour, and the AASM advises moving bedtime 15 to 20 minutes a night for the nights before. The step selector above already offers both sizes.
For a flight the distance is the number of time zones and the direction is set by the route. Eastward trips ask the clock to advance, which is the slow direction; westward trips ask it to delay.
For a child the same arithmetic holds with smaller steps. Pick 15 minutes, move meals and the bedtime routine by the same amount, and keep morning light on the same schedule as the alarm.
Questions people ask
- How many nights does it take to move my sleep by four hours?
- It depends on the step you choose. At 30 minutes a night it is 8 nights, at 60 minutes it is 4. The 60-minute step is the largest an earlier move should use, according to Eastman and Burgess.
- Should I move bedtime and alarm together?
- This planner does, so the length of your sleep stays steady. If you only move the bedtime and leave the alarm, you lose sleep on every night of the plan.
- Do I need bright light for this to work?
- The plan works on the schedule alone, but the studies on how fast the clock moves used timed bright light. The light row in the table is the part to take seriously when the gap is three hours or more.
- Is the calendar file stored anywhere?
- No. Your browser builds it from the table on the page and saves it to your device. Nothing is uploaded and there is no email form.
Sources
- How to travel the world without jet lag — Sleep Medicine Clinics 4(2):241-255, 2009 (Eastman C.I., Burgess H.J.)
- Circadian rhythm sleep disorders: part I, basic principles, shift work and jet lag disorders — Sleep 30(11):1460-1483, 2007 (Sack R.L. et al., AASM review)
- A phase response curve to single bright light pulses in human subjects — The Journal of Physiology 549(3):945-952, 2003 (Khalsa S.B.S. et al.)
- Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed — Journal of Clinical Sleep Medicine, 2013 (Drake C. et al.)
- Social jetlag and obesity — Current Biology, 2012 (Roenneberg T. et al.)
- Recommended amount of sleep for a healthy adult: a joint consensus statement of the AASM and Sleep Research Society — Sleep 38(6):843-844, 2015 (Watson N.F. et al.)
General information from population studies (NIH, CDC, NSF, AASM). It is not medical advice and does not replace a clinician who knows you.