Starting work earlier than usual is linked with less sleep. In a Journal of Occupational Health study of 143 Japanese employees, published online 26 October 2026, each hour work began earlier than a person’s own usual time was linked with about 6.5 minutes less measured sleep, while bedtime barely moved. Habitual early starters did not sleep measurably less.
Key takeaways
- A 2026 field study in the Journal of Occupational Health (Ikeda and colleagues, Japan) followed 143 full-time employees for 10 days with a sleep tracker worn at the waist (actigraphy) and twice-daily blood pressure checks. It was observational, so it shows links, not cause.
- On days when work began 1 hour earlier than a person’s usual start, measured sleep was about 6.5 minutes shorter: lights-off moved only about 6 minutes earlier, while getting out of bed moved about 14 minutes earlier.
- People whose start time was early on average went to bed about 38 minutes earlier for each hour, and their sleep was not measurably shorter. They did report more fatigue before bed.
- Each extra hour of spread in a person’s start times was linked with about 2 to 3 mmHg higher blood pressure, both before bed and after waking.
- The one change: when your start time moves earlier, move lights-off earlier by the same amount, and keep your start time as steady as your work allows.
What did the 2026 work start time study find?
Earlier-than-usual starts were linked with shorter sleep, and irregular starts with higher blood pressure. The study by Hiroki Ikeda, Tomohide Kubo and colleagues separated two questions that are usually blurred: what happens on the days a person starts earlier than their own norm, and how people who habitually start early differ from people who start later.
The 143 employees, 84% men with an average age of 48, worked full time with a standard two-days-off week. From 1 to 10 February 2025 they logged their work start and finish times in a phone app, measured their blood pressure after waking and before bed, and wore a waist actigraph each night. The median start time on workdays was about 7:48 AM, and 848 workdays had usable data.
| Comparison (per 1 hour earlier) | Sleep | Lights-off | Out of bed | Blood pressure after waking |
|---|---|---|---|---|
| A person’s own earlier-than-usual day | about 6.5 min less | about 6 min earlier | about 14 min earlier | about 0.8 mmHg higher (systolic) |
| People who start early on average | no clear difference | about 38 min earlier | about 45 min earlier | no clear difference |
The figures come from adjusted models accounting for age, sex, body mass index, smoking, alcohol, working hours, commute time, working from home, overtime at home and after-hours work messages.
Why might an early start mean less sleep?
Bedtime is harder to move than wake time. An alarm can pull waking earlier in one step, but the body clock, family evenings and household tasks hold bedtime in place, so a one-off early start tends to come out of sleep.
A 2010 nationally representative survey of 5,489 people in Sweden (Åkerstedt, Kecklund and Selén, Chronobiology International) found the same pattern: as start times moved earlier, rising times moved earlier but bedtimes changed very little, and sleep fell below 5 hours for starts between 3 AM and 4:30 AM. The 2026 study adds that shorter sleep showed up only when the early start was the exception rather than the rule. The authors suggest that habitual early starters may have adapted their routine, and that some may simply be morning types; chronotype was not measured, so the two cannot be told apart.
Sleep was short across the board. Median measured sleep was about 298 minutes, just under 5 hours a night, well below the 7 hours or more that the American Academy of Sleep Medicine and Sleep Research Society recommend for adults. The tracker only counted main nighttime sleep, so naps on the commute were missed.
Are irregular start times linked with blood pressure?
In this study, a less predictable start time was linked with higher blood pressure. For every extra hour in the spread of a person’s start times over the 10 days (the interquartile range), systolic pressure was about 2.4 mmHg higher before bed and 2.8 mmHg higher after waking, with diastolic pressure about 2 mmHg higher at both times. Irregular start times were not linked with shorter sleep.
The authors call these effects modest and say their clinical meaning should be read with caution. They fit other work. In a 2022 Sleep study of 20 newly hired bus operators in the United States (McHill and colleagues), 62% of those moved onto early-morning shifts lost the healthy overnight dip in blood pressure within 90 days, and the change tracked how variable their sleep timing became. Among 1,992 adults in the Multi-Ethnic Study of Atherosclerosis (Huang, Mariani and Redline, 2020), those whose sleep-onset times varied the most across a week (a standard deviation above 90 minutes) had about twice the risk of a cardiovascular event over a median 4.9 years as those whose varied by 30 minutes or less, an association that held after adjusting for sleep length.
What are the limits of the study?
It is a 10-day observational study, so it cannot show that early starts cause shorter sleep or higher blood pressure. Start times were self-reported, the volunteers were recruited because they started early, started irregularly or worked long hours, and most were men, so the results may not carry over to the wider workforce. Blood pressure was taken at home without a fixed rest period, and exercise and bathing times were not recorded.
What is the one change to make?
When your start time moves earlier, move lights-off earlier by the same amount, and keep your start time as steady as your work allows. The study did not test this step; it is a practical way to act on what it found, since habitual early starters who shifted their whole evening did not sleep measurably less.
- Build your sleep window back from your earliest regular start: 7 hours or more of sleep, plus time to get ready and travel.
- Before an earlier-than-usual start, bring dinner, the wind-down and lights-off forward by the same amount, not just the alarm.
- Where you have a say, ask for start times that stay within the same hour across the week.
- Keep wake time close to your workday wake time on days off, so early mornings feel routine.
More on a steady week: How to Fix Your Sleep Schedule: Anchor, Light, 15 Min and What Is Social Jetlag? What a 2026 Wearable Study Found. On evening email: Working Before Bed and Sleep: What a 2026 Study Found. Working nights instead? See Night Shift Schedule: How to Plan Sleep, Meals and Light. Curious when your own body clock runs? Take the Body Clock Type quiz.
Your day on My BodyClock
The day above on My BodyClock is built for a steady 7 AM start. Lights-off at 9:30 PM and an alarm at 5:30 AM give an 8-hour sleep window, getting ready, breakfast and the commute fill the hour and a half before work, and a walk after lunch adds daylight. Dinner wraps up by 6 PM, and the last hour before bed is for winding down and setting out what the morning needs. The same start, bedtime and wake time hold all week, so an early morning is the routine, not the exception.
Plan your own steady start in Owaves: My BodyClock on the App Store, or join the Android waitlist.
FAQ
Does starting work early mean less sleep?
It can, mainly when the early start is unusual for you. In the 2026 study of 143 Japanese employees, each hour work began earlier than a person’s usual time was linked with about 6.5 minutes less sleep. People who habitually started early went to bed earlier and did not sleep measurably less.
How much earlier should I go to bed for an early start?
Move lights-off earlier by the same amount as your wake time, so your sleep window stays the same length. In the 2026 study, people moved their bedtime only about 6 minutes for each hour of earlier start, and their measured sleep was shorter.
Are irregular work hours bad for blood pressure?
In the 2026 study, each extra hour of spread in a person’s start times was linked with about 2 to 3 mmHg higher blood pressure before bed and after waking. The study was observational and the authors call the effect modest, but larger studies also link irregular sleep timing with heart health.
What time should I go to bed if I start work at 7 AM?
Count back from your start: travel and getting ready, then at least 7 hours of sleep. With a 30-minute commute and an hour to get ready, that means waking around 5:30 AM and lights-off by about 10:30 PM, or 9:30 PM for 8 hours.
Sources
- Ikeda H, Kubo T, Matsumoto S, Izawa S, Nishimura Y, Liu X. Associations between work start time with objective sleep and health-related outcomes: a 10-day field study distinguishing within-person and between-person effects. Journal of Occupational Health, published online 26 October 2026. doi:10.1093/joccuh/uiag068. https://doi.org/10.1093/joccuh/uiag068
- Åkerstedt T, Kecklund G, Selén J. Early morning work — prevalence and relation to sleep/wake problems: a national representative survey. Chronobiology International, 2010;27(5):975-986. doi:10.3109/07420528.2010.489001. https://pubmed.ncbi.nlm.nih.gov/20636210/
- McHill AW, Velasco J, Bodner T, Shea SA, Olson R. Rapid changes in overnight blood pressure after transitioning to early-morning shiftwork. Sleep, 2022;45(3):zsab203. doi:10.1093/sleep/zsab203. https://pmc.ncbi.nlm.nih.gov/articles/PMC8919200/
- Huang T, Mariani S, Redline S. Sleep Irregularity and Risk of Cardiovascular Events: The Multi-Ethnic Study of Atherosclerosis. Journal of the American College of Cardiology, 2020;75(9):991-999. doi:10.1016/j.jacc.2019.12.054. https://pmc.ncbi.nlm.nih.gov/articles/PMC7237955/
- Watson NF, Badr MS, Belenky G, et al. Recommended Amount of Sleep for a Healthy Adult: A Joint Consensus Statement of the American Academy of Sleep Medicine and Sleep Research Society. Journal of Clinical Sleep Medicine, 2015;11(6):591-592. doi:10.5664/jcsm.4758. https://pmc.ncbi.nlm.nih.gov/articles/PMC4442216/
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