Optimal Sleep Schedule Calculator

An optimal sleep schedule means waking at the same time every day

Picture someone who is in bed at 12:30 AM and up at 7:00 AM on workdays, then in bed at 2:00 AM and up at 10:30 AM on Friday and Saturday nights. If it takes 15 minutes to fall asleep, the middle of sleep (mid-sleep) lands at 3:53 AM on workdays and 6:23 AM on days off. Every weekend the middle of sleep moves 2 h 30 min later, then jumps back on Monday. That gap is called social jetlag.

The calculator above takes your bedtimes and wake times for workday nights and days-off nights and works out your social jetlag, your weekly average sleep, and your corrected mid-sleep, a marker of your body clock. It also builds a steady schedule with the same wake time every day (in the example, 11:45 PM to bed and 7:00 AM up, daily) and a day-by-day plan that moves you there 15 minutes at a time. Switch the sleep timetable between Now and After and you can watch the two bars slide onto one line as social jetlag drops to zero.

Why look at the whole week instead of one night

One night has a simple answer, but the body clock is set by the times you repeat across the week. Japan's Ministry of Health, Labour and Welfare explains in its 2023 sleep guide that when people sleep in on days off to catch up and their wake time slips far later, the body clock is thrown off and produces the same jet lag as travel across time zones. Because it happens again every weekend, it is also called social jetlag. The same guide cites a survey of adults aged 40 to 64: people who slept 6 hours or more on weekdays but habitually slept in by 2 hours or more on days off did not get a lower risk of shortened life. In MCTQ (Munich Chronotype Questionnaire) data, 69% of respondents had 1 hour or more of social jetlag and about a third had 2 hours or more (Roenneberg 2012).

The US Centers for Disease Control and Prevention (CDC) sleep page includes this advice: "Going to bed and getting up at the same time every day." The American Academy of Sleep Medicine (AASM) extends it to days off: get up at the same time every day, even on weekends or during vacations.

• You sleep in on weekends: see whether you are short on workdays, how much later you wake on days off, and how many minutes of that is catch-up sleep.
• A new semester or job changes your wake time: enter a target wake time and get the bedtime and wake time for each night starting tonight.
• Mondays are the hardest: if weekend mid-sleep is hours later than on workdays, your sleep is pulled back by that much every Monday, and the number shows it.
• You wonder whether you are a morning or evening person: compare your corrected mid-sleep, which removes the catch-up share of days-off sleep, with the most common value.

How to use the calculator

1. Pick your workdays (or school days). The default is Monday to Friday, and the night before each selected day counts as a workday night.
2. Enter your workday-night bedtime and wake time. Bedtime is when you lie down with the lights off, ready to sleep.
3. Enter your days-off night bedtime and wake time, and turn on the switch if an alarm wakes you on days off too.
4. Set time to fall asleep (15 minutes by default) and your age group. The age group sets the recommended minimum sleep.
5. If your wake time has to change, enter a target wake time in the steady schedule row. Left blank, your current workday wake time is used.
6. Read the steady schedule, the social jetlag, and the 15-minute shifting plan below, then save it with Copy result or Copy link.

How it is calculated

1. Sleep onset = bedtime + time to fall asleep
2. Time asleep = wake time − sleep onset, and mid-sleep = sleep onset + time asleep ÷ 2 (rounded to the minute)
3. Social jetlag = days-off mid-sleep − workday mid-sleep
4. Weekly average sleep = (workday sleep × number of workday nights + days-off sleep × number of days-off nights) ÷ 7
5. Corrected mid-sleep = days-off mid-sleep − (days-off sleep − weekly average sleep) ÷ 2. It subtracts only when you sleep longer on days off, and it is not calculated if an alarm wakes you on days off.
6. Steady schedule: sleep length = the longer of your weekly average rounded up to 15 minutes and the age-group minimum; sleep onset = target wake time − sleep length; bedtime = sleep onset − time to fall asleep
7. Days to shift = the larger of the bedtime and wake-time gaps between your workday schedule and the steady schedule ÷ 15 minutes (rounded up)

In the example, the weekly average is (6 h 15 min × 5 + 8 h 15 min × 2) ÷ 7 = 6 h 49 min. The catch-up share on days off is (8 h 15 min − 6 h 49 min) ÷ 2 = 43 min, so corrected mid-sleep is 6:23 AM minus 43 min, which is 5:40 AM. Rounding 6 h 49 min up to 15 minutes gives 7 h, and the adult minimum is also 7 h, so to wake at 7:00 AM you fall asleep at 12:00 AM and get into bed at 11:45 PM. Moving from the 12:30 AM workday bedtime to 11:45 PM is 45 minutes, which takes 3 days at 15 minutes a day.

The example schedule at a glance

Social jetlag here is 6:23 AM − 3:53 AM = 2 h 30 min, and in the steady schedule workdays and days off match, so it falls to 0 min. Its mid-sleep of 3:30 AM is 23 minutes earlier than the current workday value, but because sleep is shared evenly across the week, weekly average sleep rises from 6 h 49 min to 7 h.

How your weekend schedule changes social jetlag

Fix workdays at 12:30 AM to bed and 7:00 AM up, change only the days-off schedule, and the results look like this (15 minutes to fall asleep, Monday to Friday workdays).

Going to bed at the same time and only waking later still creates social jetlag, and a later bedtime makes it grow fast. With the same amount of sleep on days off, a bedtime one hour later adds one hour of social jetlag. Corrected mid-sleep moves less than social jetlag because it subtracts the catch-up share.

Your body clock through corrected mid-sleep

The MCTQ treats the middle of sleep on days off without an alarm as a measure of chronotype (roughly, morning or evening type). People who are short on sleep during the week sleep longer on days off, which pushes mid-sleep later, so half of the catch-up share is subtracted as a correction (Roenneberg 2004). The scale in the calculator plots this corrected value across the range from 11 PM to 10 AM.

• Most common value: in MCTQ data centered on Germany, Switzerland, the Netherlands and Austria, the most common range of days-off mid-sleep was around 4:14 AM (14.6% of people), with 35.02% earlier and 50.38% later (Roenneberg 2007). This distribution is for uncorrected MSF, so the calculator's comparison of your corrected value with it is approximate.
• Age: mid-sleep is early in childhood, gets later from puberty, is latest around age 20 (19.5 for women, 20.9 for men), then moves earlier again (Roenneberg 2004). After 60 it is on average earlier than in childhood (Roenneberg 2007).
• Why there are no type labels: there is no official table that splits corrected mid-sleep into types at fixed times. So instead of "morning type" or "evening type", the calculator shows only how many minutes earlier or later you are than the most common value.

How to move to the steady schedule

The American Academy of Sleep Medicine (AASM) recommends getting up at the same time every day, including weekends and vacations. Japan's 2023 guide also says to wake at your usual time on weekends and days off and get daylight, and explains that morning light moves the body clock earlier (toward an earlier bedtime and wake time) while light in the evening or later pushes it later. For the pace, the calculator uses the method the AASM gives parents before school starts: shift bedtime and wake time by 15 minutes a day.

Say your wake time has to move from 7:00 AM to 6:30 AM. The steady schedule becomes 11:15 PM to bed and 6:30 AM up, and moving from the 12:30 AM workday bedtime by 1 h 15 min takes 5 days. On the first night you lie down at 12:15 AM and wake at 6:45 AM, on the second at 12:00 AM and 6:30 AM, and after that the wake time stays put while bedtime moves 15 minutes a day. During the shift, keep that day's times on days off too, so the body clock does not slide back.

Recommended sleep by age group

If your weekly average is below the age-group minimum, the steady schedule moves bedtime earlier up to that minimum; if it is above, the average is rounded up to 15 minutes and shared evenly across the days. Japan's 2023 guide recommends at least 6 hours for adults.

Common mistakes

• Mixing up bedtime and the time you fall asleep: put the time you lie down in the bedtime field and the time to fall asleep in its own field. If you entered the time you actually fell asleep, set time to fall asleep to 0 minutes.
• Counting phone time as bedtime: count from when the lights are off and you try to sleep. Time spent on your phone in bed is not time to fall asleep.
• Mixing up which nights are workday nights: if you work Monday to Friday, the five nights from Sunday to Thursday are workday nights and Friday and Saturday nights are days-off nights.
• Swapping AM and PM: sleep longer than 16 hours triggers an error, so recheck AM and PM on the bedtime.
• Adding naps: the calculation is based on one night of sleep. Naps are not added to time asleep.

Limits and cautions

• Social jetlag and corrected mid-sleep are measures used in MCTQ research and do not diagnose a sleep disorder. If you keep having trouble falling asleep or feel very sleepy during the day, talk to a sleep specialist.
• The most common mid-sleep of 4:14 AM comes from central European data. Distributions can differ by country, latitude and age.
• Fifteen minutes a day is the pace the AASM gives for children before a new school term. It is not a number showing that an adult's body clock keeps up at the same speed.
• Workdays and days off are each simplified to one schedule. If your times vary a lot by day, enter a representative value or check with a sleep diary.
• Shift work that includes night shifts, frequent waking in bed, and time awake at night are not included in the calculation.

As of the MCTQ papers, AASM guidance, Japan's MHLW guide and the CDC page were checked against the original sources on 2026-10-19. Recommended sleep amounts come from the same sources as the Sleep Time Calculator and the Sleep Debt Calculator.

Sources

• 01Roenneberg T, et al. Social jetlag and obesity. Curr Biol 2012Social jetlag = difference between days-off and workday mid-sleep (MSF-MSW); 69% had 1 hour or more and a third 2 hours or more; linked to the probability of being overweight beyond sleep duration
• 02Roenneberg T, et al. Epidemiology of the human circadian clock. Sleep Med Rev 2007Mid-sleep = midpoint between sleep onset and waking; most common MSF 4:14 (14.6%), 35.02% earlier and 50.38% later; after 60, earlier than in childhood
• 03Roenneberg T, et al. A marker for the end of adolescence. Curr Biol 2004Latest around age 20 (women 19.5, men 20.9); supplement gives MSFsc = MSF − 0.5 × (SDf − weekly average)
• 04Wittmann M, et al. Social jetlag: misalignment of biological and social time. Chronobiol Int 2006The gap between workdays and days off, between social and biological time, is named social jetlag
• 05Juda M, et al. Chronotype modulates sleep duration, sleep quality, and social jet lag in shift-workers. J Biol Rhythms 2013Sleep onset = bedtime + time to fall asleep; people who use an alarm on days off are excluded from chronotype; MCTQShift for shift work
• 06American Academy of Sleep Medicine (AASM): Healthy sleep habits"Get up at the same time every day, even on weekends or during vacations."
• 07AASM: Back-to-school sleep tips every parent should knowA few days before school starts, shift bedtime and wake time by 15 minutes a day to fit the school schedule
• 08Japan Ministry of Health, Labour and Welfare: Sleep Guide for Health Promotion 2023 (健康づくりのための睡眠ガイド2023)PDF p. 14: catch-up sleep on days off and social jetlag, and the habit of sleeping in 2 hours or more on days off; p. 18: same wake time and daylight on weekends and days off; p. 45: morning light advances the body clock, light after evening delays it
• 09Watson NF, et al. Recommended Amount of Sleep for a Healthy Adult (AASM, SRS). J Clin Sleep Med 2015"Adults should sleep 7 or more hours per night on a regular basis"
• 10Paruthi S, et al. Recommended Amount of Sleep for Pediatric Populations (AASM). J Clin Sleep Med 2016Ages 6-12: 9-12 hours; ages 13-18: 8-10 hours
• 11Hirshkowitz M, et al. National Sleep Foundation's sleep time duration recommendations. Sleep Health 2015Adults 7-9 hours, ages 65+ 7-8 hours
• 12US Centers for Disease Control and Prevention (CDC): About sleepAdvice: "Going to bed and getting up at the same time every day."

Frequently asked questions

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