Sleep schedule off? Fix your wake time first, then move bedtime in 15-minute steps

In a lab with no windows and no clocks, the average person’s body keeps a day of 24 hours and 11 minutes. That figure comes from a 1999 Harvard study of 24 healthy adults, published in the journal Science. Those extra 11 minutes help explain why a sleep schedule slides later so easily, and why it rarely slides back on its own.

Most people try to fix it at bedtime. Start at the other end. Tonight, choose one wake time and set an alarm for it on all 7 days, Saturday and Sunday included, then keep it for a week before you change anything else.

Why the morning sets the clock

You can’t order yourself to fall asleep at 11 p.m. when your body expects 1 a.m. You can get out of bed at 7:00, though, and light in the first hours after waking has the strongest effect on when your body clock runs.

Light reaching your eyes early in the day pulls the clock earlier, and bright light late in the evening pushes it later. A wake time that wanders from day to day sends mixed signals. A fixed one gives the clock the same cue every morning. The drive to sleep also starts building from the moment you get up, which means getting up at the same time makes you sleepy at about the same hour each night.

Bedtime follows once those two signals line up, and that’s why the steps below move it last.

Before you start, check last week. Write down the time you got up on each of the 7 days, and if the earliest and latest are more than an hour apart, that spread is the drift this plan closes.

How much sleep to plan for

The American Academy of Sleep Medicine and the Sleep Research Society brought 15 sleep experts together in 2015, and their joint statement says adults aged 18 to 60 should sleep 7 or more hours a night on a regular basis.

Plenty of people miss that mark. The CDC’s 2014 health survey reached 444,306 adults, and only 65.2% of them reported getting at least 7 hours. That left about 1 in 3 short.

To find your target bedtime, count back from the alarm. A 7:00 a.m. wake time and a goal of 8 hours in bed points to 11 p.m., which leaves room to fall asleep and still clear 7 hours.

1. One wake time, all 7 days

Use the time your weekdays already demand. If you leave for work at 7:45, the alarm goes off at 7:00 on Tuesday, on Saturday and on every day in between.

The weekend is where most schedules break. Till Roenneberg’s team at Ludwig Maximilian University in Munich calls the gap between your body’s internal time and the hours that work and school impose “social jetlag”. In a 2012 paper in Current Biology, built on the team’s large sleep-timing questionnaire, they reported that about two thirds of people carry a significant gap of this kind.

Sleeping until 10:00 on Saturday after a week of 7:00 alarms is a lot like flying 3 time zones west for the weekend. Monday morning flies you back.

Keep your weekend wake time within about an hour of the weekday alarm, so 8:00 at the latest for a 7:00 alarm. After a short night, get up anyway, since the tired evening that follows tends to make the next bedtime easier. Count this step as working once you’ve made the window 7 mornings in a row.

2. Get outside within an hour of waking

Spend 10 to 30 minutes outdoors within an hour of your alarm. A walk to the corner counts, and so does drinking your coffee on the front step or taking the dog around the block. Cloudy mornings count too.

The best evidence for this step comes from Kenneth Wright’s sleep lab at the University of Colorado Boulder. In a 2013 study in Current Biology, 8 adults spent a summer week camping in the Rocky Mountains. They took in about 4 times their usual daytime light, and their melatonin, the hormone that rises before sleep, started nearly 2 hours earlier, close to sunset. The shift showed up in night owls and early birds alike.

A 2017 follow-up from the same lab found that one summer weekend outdoors moved melatonin 1.4 hours earlier. That was about 69% of the shift from the full week.

A winter trip in that study showed how dim ordinary life is. The campers took in 13 times as much light as during their weeks at home, even though they had been going outside during those weeks too.

You won’t be camping on a Tuesday, so aim for the dose. A few minutes by a window is a small signal, and 10 to 30 minutes outside is a much larger one. If it’s still dark at your wake time in winter, go out as soon as the sky turns light.

3. Move bedtime 15 minutes every few nights

With the wake time and the morning light in place, start moving bedtime. Go 15 minutes earlier, hold that for 2 or 3 nights, then take the next 15. For most people a bigger jump just means lying awake at the new hour, because the body clock hasn’t moved yet.

Example: you fall asleep around 1 a.m. now, the alarm stays at 7:00 a.m. throughout, and you want lights out at 11 p.m. You hold each step for 3 nights.

Midnight arrives on night 13 and 11 p.m. on night 25, a little over 3 weeks in all.

Time in bed grows from 6 hours to 8 along the way and passes the 7-hour mark about halfway through. That slow pace is the point of the plan.

If a step goes badly and you’re still awake an hour after lights out, hold that bedtime for 2 more nights before moving on. You can take the next step once you’re falling asleep near the new time on most nights.

4. Dim the last hour

The last hour before bed should look like evening. Turn off the overhead lights, keep one lamp on, and put your phone on a charger outside the bedroom. Wright’s advice for people who can’t get away to camp was the same pair of moves: more bright natural light by day, and smartphones and laptops off well before bedtime.

One hour is the minimum. In 2022, 18 sleep and lighting researchers published consensus recommendations in the journal PLOS Biology calling for dim light during the 3 hours before bed and a bedroom as dark as possible during sleep.

Three dim hours is hard in a home with homework and dishes. Start with one. If the TV stays on, turn the room lights down around it.

Set the lamp-only hour to start at the same clock time each night, one hour before that week’s lights out.

Signs it’s more than a schedule

A fixed wake time fixes drift. It won’t fix a sleep disorder, and some signs call for a doctor:

• loud snoring, or waking up gasping or choking
• feeling sleepy through the day after 7 or more hours in bed
• sleeplessness that lasts for weeks even on a steady schedule

The American Academy of Sleep Medicine defines chronic insomnia as trouble sleeping, with daytime effects, at least 3 nights a week for 3 months. You don’t need to wait that long to ask about it.

This guide leaves out melatonin pills and other sleep aids on purpose, and you should ask your doctor before trying either. If you do book a visit, bring 2 weeks of notes on when you went to bed, when you got up and how you felt the next day.

Start tomorrow morning

Set the alarm tonight, then run these 3 checks tomorrow with the example’s times or your own:

• At 7:00 a.m., get up when the alarm goes off, even after a rough night.
• By 8:00 a.m., spend at least 10 minutes outside.
• At midnight, turn off the overhead lights and put the phone on its charger in another room, one hour before a 1 a.m. lights out.