One in seven workers clocks in during off-hours, and sleep is the first thing to anchor

Key takeaways

• In 2024 and 2025, about 15% of U.S. wage and salary workers worked outside regular daytime hours, and 9% learned their schedule a day or less ahead, the Bureau of Labor Statistics reports¹.
• On a closed test track, 6 of 16 night-shift workers had near-crashes during a two-hour drive after a night shift, and none did after a night of sleep³.
• In a 1981 lab study, keeping one 4-hour sleep block at the same clock time every day helped hold body rhythms steady⁶.
• NIOSH advises night workers to seek bright light early in a shift and dim it later, and calls dark glasses on the ride home safest when someone else drives⁸¹⁰.
• A 2023 Cochrane review found that capping shifts at 16 hours in 80-hour workweeks probably cuts sleepiness and may add sleep, while proof that rotation direction matters is very uncertain¹².

In a study published in 2016, researchers put 16 night-shift workers behind the wheel on a closed test track at the Liberty Mutual Research Institute for Safety³. Each person drove for two hours in the daytime on two occasions: once after a normal night’s sleep and once after working a night shift³.

After sleep, nobody had a near-crash. After a night shift, 6 of the 16 drives included at least one, 11 in all, and 7 drives were stopped early for safety³.

On those drives, their blinks grew longer, slow eye movements nearly doubled, and their cars drifted out of the lane about twice as often³.

That drive home is one hidden cost of a schedule that runs against the body’s clock. Millions of people live with one, from nurses and hotel staff to parents up with a baby in the middle of the night.

You often can’t change the schedule, but you can change how you sleep around it. The medical condition called shift work disorder gets its own article later in this series.

About 1 in 7 workers keep off-hours, and some get a day’s notice

In September 2026, the Bureau of Labor Statistics released new figures on work schedules for 2024 and 2025¹. About 85% of wage and salary workers kept regular daytime hours¹.

The other 14.8%, about 1 in 7 by our rounding, worked something else: 5.3% on evenings, 3.4% on nights, and the rest on rotating, split, irregular or other schedules¹. Out of about 151 million wage and salary workers, that’s roughly 22 million people, by our math from the bureau’s table¹. In 2017 and 2018, the share was 16.4%, about 1 in 6².

Off-hours work was most common in leisure and hospitality, at 40%, followed by transportation and utilities, at 25%¹.

Many people don’t choose it. The top reason given was the nature of the job, at 37%¹. Personal preference came next, at 24%, and better family arrangements at 13%¹.

Irregular can also mean unpredictable. Most workers, 59%, knew their schedule four weeks or more ahead, but 9% learned it a day or less in advance¹.

Your body clock doesn’t flip just because your shift does

Your brain keeps a roughly 24-hour clock, and light is its main signal. Morning light reaching the eyes sets off hormone changes that tell the body it’s time to be alert¹⁰. Our article on circadian rhythms explains more.

Night work asks you to stay awake when that clock expects sleep, then sleep while daylight pushes you awake. The National Institute for Occupational Safety and Health (NIOSH) says most people struggle to adjust to night work¹¹. Many permanent night workers switch back to days on their days off, so their sleep keeps flipping¹¹.

NIOSH warns that switching back and forth once or more a week can leave you in a “perpetual state of jet lag“⁷.

Nights aren’t the only trouble spot. A 2010 review of field studies in the Scandinavian Journal of Work, Environment & Health found that night shifts, early-morning shifts and quick returns, meaning short breaks between one shift and the next, all went with shorter sleep and more sleepiness¹³. So did shifts longer than 16 hours and workweeks longer than 55 hours¹³.

What the cancer label does and doesn’t mean

In June 2019, 27 experts from 16 countries met at the International Agency for Research on Cancer (IARC), part of the World Health Organization⁵. They classified night shift work as “probably carcinogenic to humans,” Group 2A, the same rating IARC gave shift work in 2007⁴⁵.

The human studies tied night work to cancers of the breast, prostate, colon and rectum, though the panel couldn’t exclude bias or other explanations⁴. Evidence from animals and lab experiments was stronger⁴. The label describes how sure IARC is that something can cause cancer, not how big the risk is⁴. Hairdressing and barbering carry the same rating⁴.

Manolis Kogevinas of ISGlobal, who chaired the panel’s epidemiology group, suggested avoiding night work over many years and schedules with many nights a week⁵. If you’re worried, talk with your doctor about your usual cancer screening.

An anchor sleep gives your clock one fixed point

In 1981, researchers David Minors and James Waterhouse presented a study at a NIOSH symposium on work and sleep schedules⁶. Their volunteers were students who split sleep into two 4-hour blocks a day⁶.

One block stayed at the same clock time every day: the “anchor.” The other moved around⁶.

When the anchor fell between midnight and 4 a.m., or between 4 a.m. and 8 a.m., body rhythms quickly settled into a steady 24-hour pattern and held it⁶. Anchors in the daytime worked less well at first, and rhythms stretched longer than 24 hours⁶. A group that slept a full eight hours at irregular times drifted to an average cycle of about 24.5 hours⁶.

It was a small lab study of students, not workers. But the same idea runs through NIOSH’s advice today.

NIOSH lays out a middle path for night workers⁷. After a shift, head to bed the moment you’re home, often around 8 in the morning, and stay there as long as sleep lasts. Your days off shift later too, with a bedtime around 3 or 4 in the morning and a wake time around noon or 1⁷. The overlap, 8 until noon, gets slept every day, which makes it your anchor.

NIOSH also warns against staying awake all day before your first night shift, or all day after your last one, because both leave you awake far too long⁷. Instead, sleep whenever you get the chance, naps included⁷.

Parents and caregivers can tag-team an anchor

Night duty with a baby or a sick relative is an irregular schedule, too. Our article on busy parents covers the long sleep loss after a new baby.

The anchor idea adds one twist: make each adult’s protected block land at the same clock hours every night. One partner might sleep from 10 until 3 while the other handles wake-ups, and then they trade.

No study has tested this in families, so treat it as a sensible experiment. If you care for someone alone, ask a relative, friend or respite service to cover one fixed block a few nights a week.

Treat light and darkness as your two strongest tools

Natural-health traditions have long honored the rhythm of sun and night. When your job breaks that rhythm, light and darkness are still free tools, and you can choose when to use each.

For permanent night workers, NIOSH suggests spending as much of the first half of the shift as you can in brightly lit areas⁸. You don’t need to sit in front of a lamp⁸. In the second half, cut back on bright light so sleep comes easier after work, unless you’re very sleepy, when light can help keep you alert⁸.

Sunglasses on the way home: helpful, with a catch

One page of NIOSH’s training for nurses suggests putting on blue-blocking or very dark wraparound sunglasses before you leave work and keeping them on until you’re in your dark bedroom⁹. That may help you sleep a bit longer⁹.

Two other pages in the same training add a caution. Some researchers worry that dark lenses block light’s alerting effect and could make a sleepy driver sleepier, so NIOSH calls it safest to wear them only when someone else drives⁸¹⁰.

Make day feel like night

Your bedroom should be very dark¹⁰. NIOSH suggests blackout shades on bedroom and bathroom windows, blocking light under doors, or an eye mask¹¹. For bathroom trips, a dim red nightlight is less alerting than white light¹⁰.

Skip screens for about an hour before bed, and keep your phone from waking you¹⁰. Our article on darkness covers bedroom light in detail.

Evening-shift workers face a different problem: no buffer between work and bed. NIOSH suggests winding down with a warm shower and relaxation, sleeping 7 hours or more, then getting into bright light after you wake¹¹. That light helps your body clock lock in your sleep times¹¹.

The drive home needs its own plan

The track study’s authors noted that more than 9.5 million Americans work overnight or rotating shifts, and about a third of U.S. commutes last longer than 30 minutes³. If you’re very sleepy, NIOSH says don’t drive⁹. Its options include:

• a ride from a family member, friend or coworker;
• a taxi or public transit (some hospitals pay for taxis when nurses are too sleepy to drive);
• a carpool;
• a room near work where you can sleep;
• caffeine followed right away by a short nap before you drive⁹.

Our articles on naps and caffeine timing explain that last pairing.

Evening workers have their own risk. NIOSH notes that driving after 1 a.m., near the body’s low point, is riskier, especially with alcohol in your system¹¹. A drink after work may help you fall asleep, but it can disrupt staying asleep¹¹. NIOSH advises against driving after any alcohol past midnight¹¹.

Better schedules help, but the proof is thinner than the advice

Shift workers often hear that schedules should rotate “forward,” from mornings to evenings to nights. A 2023 Cochrane review of 11 studies with 2,125 workers tested that idea and others¹².

Forward rotation made little or no difference to sleep quality or sleep length, though it may have reduced sleepiness on shift¹². Faster rotation may have cut sleep by about 23 minutes a day¹². The reviewers rated all of this very low certainty, meaning the true effect could be quite different¹².

One change held up better. In two randomized trials, capping shifts at 16 hours in 80-hour workweeks may have added about 44 minutes of sleep a day, with low certainty, and probably reduced sleepiness, with moderate certainty¹². A randomized trial assigns people to groups by chance, so differences are more likely caused by the change itself.

The 2010 review found that switching from slow backward rotation to fast forward rotation improved alertness and, to some degree, sleep¹³.

NIOSH offers rules of thumb for schedule makers¹¹:

• After five 8-hour or four 10-hour shifts in a row, plan one or two full days off.
• After three 12-hour shifts in a row, consider two days off.
• Keep runs of night shifts short, and keep evening and night shifts to 8 hours or less when possible.
• Let workers help set schedules, with limits that block risky patterns.

If you have a say, ask for enough hours between shifts to sleep 7 to 8 hours, which NIOSH says most people need¹⁴.

Sample sleep plans for four common schedules

These plans combine the guidance and research above. Times are examples, so shift them to fit your hours.

Schedule	Main sleep	Anchor and days off	Light and dark	Watch out for
Night shift (11 p.m. to 7 a.m.)	Sleep as soon as you get home, from about 8 a.m., as long as you can7	Keep 8 a.m. to noon; on days off, sleep about 3 or 4 a.m. to noon or 1 p.m.7	Bright light in the first half of the shift, dimmer in the second; dark glasses only if you’re not driving810	Don’t stay awake all day before your first night7; plan the drive home39
Evening shift (3 to 11 p.m.)	About 1 a.m. to 8 or 9 a.m., 7 hours or more11	Keep the same bedtime on days off	Blackout shades; bright light after waking11	Alcohol and driving after midnight11
Rotating shifts	Sleep after each night shift as you would on nights7	After your last night, don’t stay up all day7	Match light to whichever shift you’re on8	Ask for forward rotation and rest days after long runs1112
Early start (5 a.m.)	Count back 7 to 8 hours from your alarm to set bedtime14	Keep your wake time within an hour on days off	Dim lights and screens in the evening; get light soon after waking10	Early shifts and quick returns tend to shorten sleep13

What the evidence shows

Strategy	What studies found	Evidence level
A daily anchor sleep at the same clock time	Steadier rhythms in a small 1981 lab study of students; built into NIOSH guidance67	Promising but early
Bright light early in a night shift, less light late	Recommended by NIOSH; we didn’t find large field trials to cite here8	Promising but early
Dark or blue-blocking glasses on the way home	May help day sleep, but experts worry about drowsy driving910	Promising but early for sleep; avoid when driving
Forward or faster shift rotation	Little or no difference in sleep; possibly less sleepiness; very low certainty1213	Not enough evidence
Capping shifts at 16 hours	Less sleepiness (moderate certainty) and maybe 44 more minutes of sleep a day, in just two trials of 80-hour workweeks12	Promising but early
Driving home drowsy after a night shift	Near-crashes in 6 of 16 drives on a test track, none after sleep3	Evidence says no, or unsafe
Alcohol to fall asleep after a shift	Helps sleep come faster but disrupts staying asleep, per NIOSH11	Evidence says no, or unsafe

When to get help

Some tiredness comes with the job, but certain signs are worth a doctor’s visit. The National Heart, Lung, and Blood Institute (NHLBI) suggests talking with your doctor if you:

• often feel sleepy during the day¹⁵;
• don’t wake up feeling refreshed and alert¹⁵;
• are having trouble adapting to shift work¹⁵.

Tell your doctor how often you doze off or fight to stay awake during routine tasks, especially driving, and bring a sleep diary from the past few weeks¹⁵. Insomnia counts as chronic at three or more nights a week for three months, but don’t wait that long if poor sleep is hurting your daily life¹⁵. NIOSH adds that workers on rotating shifts who struggle to adjust can consult a sleep disorders specialist¹⁴.

And never drive when you’re fighting sleep; use the ride-home options above⁹. Our later article on shift work disorder explains what an evaluation involves.

Questions readers ask

The bottom line

An irregular schedule is common, and many people don’t get to choose it. Your body clock won’t fully flip for nights, but you can give it steady signals: one anchor sleep at the same hours every day, bright light when you need to be awake, deep darkness when you need to sleep.

Take the drive home most seriously, and plan a ride or a nap before you need one. Ask for schedules with sane limits, and enlist your household to guard your sleep.

Related reading

• Full-time workers average under three free hours a workday, so build health into the rest
• Busy parents need a few anchors more than a perfect routine
• Sleep trackers count your hours well, but their sleep stages are rough guesses
• Most of us misjudge our own habits, and a one-week audit shows the gaps

Sources

1. U.S. Bureau of Labor Statistics. “Job Flexibilities and Work Schedules — 2024-2025” (news release USDL-26-1533 and Table 7). BLS, September 24, 2026. bls.gov and bls.gov
2. Woods RA. “Job Flexibilities and Work Schedules in 2017–18.” BLS Spotlight on Statistics, April 2020. bls.gov
3. Lee ML, et al. “High risk of near-crash driving events following night-shift work.” Proceedings of the National Academy of Sciences, 2016;113(1):176–181. stacks.cdc.gov
4. International Agency for Research on Cancer. “IARC Monographs Meeting 124: Night Shift Work (4–11 June 2019). Questions and Answers.” IARC, July 5, 2019. iarc.who.int
5. ISGlobal. “IARC Retains ‘Probably Carcinogenic’ Classification for Night Shift Work.” July 15, 2019. isglobal.org
6. Minors DS, Waterhouse JM. “Anchor sleep as a synchronizer of rhythms on abnormal routines.” In: Proceedings of a symposium on variations in work-sleep schedules. NIOSH Publication No. 81-127, 1981:493–516. stacks.cdc.gov
7. National Institute for Occupational Safety and Health. “NIOSH Training for Nurses on Shift Work and Long Work Hours,” Module 9, page 6 (night shift sleep). CDC, reviewed March 31, 2020. cdc.gov
8. National Institute for Occupational Safety and Health. “NIOSH Training for Nurses on Shift Work and Long Work Hours,” Module 9, page 3, “Light.” CDC, reviewed March 31, 2020. cdc.gov
9. National Institute for Occupational Safety and Health. “NIOSH Training for Nurses on Shift Work and Long Work Hours,” Module 9, page 4, “Light (Continued).” CDC, reviewed March 31, 2020. archive.cdc.gov
10. National Institute for Occupational Safety and Health. “NIOSH Training for Nurses on Shift Work and Long Work Hours,” Module 6, page 7, “Improve Sleep by Avoiding Light.” CDC, reviewed March 31, 2020. cdc.gov
11. National Institute for Occupational Safety and Health. “NIOSH Training for Nurses on Shift Work and Long Work Hours,” Module 5, page 5 (work schedule guidelines) and Module 9, page 7, “Evening Shift.” CDC, reviewed March 31, 2020. cdc.gov and archive.cdc.gov
12. Hulsegge G, Coenen P, Gascon GM, et al. “Adapting shift work schedules for sleep quality, sleep duration, and sleepiness in shift workers.” Cochrane Database of Systematic Reviews, 2023;9:CD010639. pubmed.ncbi.nlm.nih.gov
13. Sallinen M, Kecklund G. “Shift work, sleep, and sleepiness: differences between shift schedules and systems.” Scandinavian Journal of Work, Environment & Health, 2010;36(2):121–133. sjweh.fi
14. National Institute for Occupational Safety and Health. “NIOSH Training for Nurses on Shift Work and Long Work Hours,” Module 5, page 1, and Module 8, page 1. CDC, reviewed March 31, 2020. archive.cdc.gov and cdc.gov
15. National Heart, Lung, and Blood Institute. “Sleep Deprivation and Deficiency: Diagnosis” (updated July 30, 2026) and “Insomnia: Diagnosis” (accessed October 2026). NIH. nhlbi.nih.gov and nhlbi.nih.gov