Yes, regular long sleep was linked with a higher risk of brain bleeds in a 2026 study. Among 314,236 UK Biobank adults, published in Frontiers in Neurology, sleeping more than 9 hours a day carried a 55% higher risk of spontaneous intracerebral hemorrhage than 7 to 9 hours. Risk was lowest at about 7 to 8 hours.
Key takeaways
- A prospective UK Biobank study of 314,236 adults, published in Frontiers in Neurology on 26 October 2026, tracked who went on to have a spontaneous intracerebral hemorrhage, a stroke caused by bleeding inside the brain.
- Compared with 7 to 9 hours a day, sleeping more than 9 hours was linked with a 55% higher risk, and sleeping under 7 hours with a 14% higher risk.
- The lowest risk sat at about 7 to 8 hours of sleep a day, a U-shaped pattern that a hospital dataset of 827 people in China repeated.
- The study was observational: long sleep may partly be a sign of illness that is already there, so it shows a link, not proof that extra sleep causes bleeds.
- One change to make: give sleep a fixed window of about 8 hours in bed, enough for 7 to 8 hours asleep, and keep it on workdays and days off.
What did the 2026 sleep duration study find?
Both short and long sleepers were more likely to have a brain bleed, and the link was stronger and steadier for long sleep. A team led by neurosurgeons at Jinjiang Municipal Hospital (Shanghai Sixth People’s Hospital Fujian) in China analyzed UK Biobank records, then checked the pattern in their own hospital patients.
| Study detail | What it was |
|---|---|
| Journal | Frontiers in Neurology, published 26 October 2026 |
| Design | Prospective cohort study (observational), plus a cross-sectional hospital comparison |
| People | 314,236 UK Biobank adults with no brain bleed at the start; 312 hospital patients with a bleed and 515 neurosurgical patients without one |
| Sleep measure | Self-reported hours a day, asked once: short (under 7), normal (7 to 9), long (over 9) |
| Follow-up | From recruitment (2006 to 2010) to the end of 2022 |
| Adjusted for | Age, sex, ethnicity, education, income, deprivation, body mass index, smoking, alcohol, physical activity, other illnesses, diabetes and high blood pressure |
| Main result | Long sleep: 55% higher risk; short sleep: 14% higher risk |
During follow-up, 1,387 people, about 4 in every 1,000, had a spontaneous intracerebral hemorrhage. Long sleep was uncommon: 3.0% of the people who had a bleed reported it, against 1.8% of those who did not. In the hospital comparison, the odds of a bleed were 2.05 times higher with long sleep and 1.49 times higher with short sleep.
Is sleeping 9 hours or more bad for you?
It is linked with higher risk in large studies, but it may be a signal rather than the cause. The authors say long sleep may partly reflect hidden illness that also raises the risk of a bleed, and they ask readers to interpret the long-sleep result with caution.
Several checks point the same way, though. When the researchers also adjusted for medicines, blood pressure, self-rated health, depression and frailty, the long-sleep link shrank but held, at 43% higher risk. Leaving out bleeds in the first 3 years, when hidden illness is most likely, changed the results only modestly, though the authors note this only partly rules out hidden illness. Short sleep was the less robust finding: its link faded in some sensitivity analyses.
The pattern also matches earlier work. A 2023 BMC Neurology study of 409,156 adults in the China Kadoorie Biobank found the lowest stroke and heart risks at 7 to 8 hours, and a 23% higher risk of intracerebral hemorrhage among people sleeping 10 hours or more.
Why might long sleep be linked with brain bleeds?
No one knows yet. The researchers tested a blood inflammation score as a possible go-between, and it neither explained nor reliably changed the link. Sleep was asked about once, as a single number, so the study could not tell apart long sleep from poor sleep, sleep apnea, shift work or daytime naps. The authors suggest sleep duration may be a useful marker of who is more susceptible to this kind of bleed.
How much sleep should adults aim for?
Most adults should aim for at least 7 hours a night, and the 2026 study found the lowest risk at about 7 to 8. The American Academy of Sleep Medicine and Sleep Research Society consensus recommends 7 or more hours on a regular basis. It notes that more than 9 hours may suit young adults, people recovering from lost sleep and people who are ill, and that for everyone else it is uncertain whether regular sleep over 9 hours carries health risk.
| Sleep a day | What the 2026 study linked it with |
|---|---|
| Under 7 hours | 14% higher brain bleed risk (modest, less robust) |
| 7 to 9 hours | Reference group |
| About 7 to 8 hours | Lowest estimated risk |
| Over 9 hours | 55% higher brain bleed risk |
What is the one change to make?
Give sleep a fixed window of about 8 hours in bed, enough for 7 to 8 hours asleep, and keep it on workdays and days off. It is a step toward the range the evidence favors, not a treatment, and the 2026 study did not test it.
- Pick a wake time you can keep every day, then count back 8 hours for lights out, such as 10:45 PM to 6:45 AM.
- Put both on My BodyClock as one Sleep block, with a wind-down before it.
- Get daylight and movement soon after waking, which makes a steady wake time easier to hold.
- If you regularly sleep more than 9 hours and still wake tired, mention it to a doctor.
For a step-by-step reset, read How to Fix Your Sleep Schedule: Anchor, Light, 15 Min. For why steady timing matters as much as hours, see Irregular Sleep and Death Risk: What a 2026 Study Found, and for seasonal sleep need, Should You Sleep More in Winter? What a 2026 Study Found. Take the Body Clock Type quiz to see when your own sleep window falls best.
Your day on My BodyClock
The day above on My BodyClock is a workday built around one 8-hour sleep window, from 10:45 PM to 6:45 AM. A walk outside in morning daylight and breakfast start the day before focused work, lunch and an afternoon block. Strength and mobility, dinner, family time and a hobby fill the evening. Short pink Flow blocks hold getting ready, the commute and the tidy-up, and a lamp-lit Relax wind-down with screens away leads into lights out at the same time every night.
Build your own version in Owaves: My BodyClock on the App Store, or join the Android waitlist.
FAQ
Is it bad to sleep more than 9 hours?
Regular sleep over 9 hours was linked with a 55% higher risk of a brain bleed in a 2026 UK Biobank study of 314,236 adults. The authors caution that long sleep may partly reflect illness that is already there, so the link may not be causal. If you need far more sleep than usual, talk with a doctor.
How many hours of sleep is best for stroke risk?
In the 2026 study, the lowest estimated risk of spontaneous intracerebral hemorrhage was at about 7 to 8 hours a day. A 2023 China Kadoorie Biobank study of 409,156 adults also found the lowest stroke risks at 7 to 8 hours.
Is short sleep also linked with brain bleeds?
Yes, more weakly. Sleeping under 7 hours was linked with a 14% higher risk in the UK Biobank analysis, but the authors call that link modest and less robust than the one for long sleep.
Can you make up for lost sleep by sleeping longer?
The AASM and Sleep Research Society consensus notes that more than 9 hours may suit people recovering from lost sleep. A steady 7 to 8 hours, at the same times, avoids building the debt in the first place.
Sources
- Dai W, Zhu Y, Yang L, et al. Habitual sleep duration and spontaneous intracerebral hemorrhage: a prospective UK Biobank cohort study with supporting hospital-based neurosurgical data. Frontiers in Neurology, published 26 October 2026;17:1960098. doi:10.3389/fneur.2026.1960098. https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2026.1960098/full
- PubMed record of the 2026 Frontiers in Neurology study. https://pubmed.ncbi.nlm.nih.gov/43005068/
- Chen Y, Kartsonaki C, Clarke R, et al. Sleep duration and risk of stroke and coronary heart disease: a 9-year community-based prospective study of 0.5 million Chinese adults. BMC Neurology, 14 September 2023;23:327. doi:10.1186/s12883-023-03367-4. https://pubmed.ncbi.nlm.nih.gov/37710209/
- 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. Sleep, June 2015;38(6):843-844. doi:10.5665/sleep.4716. https://pmc.ncbi.nlm.nih.gov/articles/PMC4434546/
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