The short answer
In studies following nearly half a million people, those who regularly slept less than about 6 hours were 48% more likely to develop or die of coronary heart disease and 15% more likely to have a stroke. Long sleep was linked with higher risk too. Lab trials show sleep loss raises stress hormones and nervous system activity, which helps explain the link.
Moderate evidence
Trials point the same way but are small or few, or large long-term studies agree but cannot prove cause and effect. How we grade
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What do the big studies show?
The most cited evidence is a 2011 review that pooled 15 long-term studies with 474,684 people in Europe, the US and Asia, followed for 7 to 25 years. Compared with people sleeping around 7 to 8 hours:
| Sleep | Coronary heart disease | Stroke |
|---|---|---|
| Short (usually 5 to 6 hours or less) | 48% higher risk | 15% higher risk |
| Long (usually 9 hours or more) | 38% higher risk | 65% higher risk |
These are relative risks: for someone with an average risk of heart disease, a 48% increase is meaningful but not dramatic.
For blood pressure, a US study followed 4,810 adults for 8 to 10 years. Among those aged 32 to 59, sleeping 5 hours or less was linked with about twice the risk of developing high blood pressure (hazard ratio 2.10), and allowing for weight, diabetes and other factors only partly reduced the link.
Does short sleep actually cause heart problems?
We can’t be sure, which is why we grade this moderate rather than strong. People who sleep badly also tend to be more stressed, to work shifts, to smoke and drink more, and to have depression or pain, all of which affect the heart. The studies adjusted for many of these, but not everything.
There are good reasons to think sleep loss plays its own part:
- Stress hormones and nerves. When healthy young men were limited to 4 hours a night for six nights in a lab, their evening cortisol rose and the “fight or flight” side of the nervous system became more active. Both push up heart rate and blood pressure.
- Night-time dip. Blood pressure normally falls during sleep. Short or broken sleep means less time with that dip.
- Inflammation. A review of 72 studies found that disturbed sleep was linked with higher levels of inflammation markers in the blood (CRP and IL-6), which are tied to heart disease.
- Knock-on effects on weight and blood sugar.
Why does long sleep look harmful too?
Probably mostly reverse causation. Heart failure, depression, sleep apnoea and inactivity all make people sleep longer or spend longer in bed. There’s no good evidence that cutting back long sleep is good for the heart.
Where does sleep apnoea fit in?
Obstructive sleep apnoea, where the throat repeatedly closes during sleep, is a well-established cause of high blood pressure and is linked with atrial fibrillation, heart failure and stroke. Each pause in breathing drops oxygen levels and jolts the heart and blood pressure up. Many people with it don’t know. NICE recommends assessment for people with symptoms such as loud snoring, breathing pauses and daytime sleepiness, and treatment with CPAP for moderate or severe cases.
If you have high blood pressure that is hard to control, it is worth asking your GP whether sleep apnoea could be part of the picture.
What can you do?
- Aim for 7 to 9 hours on most nights. See how much sleep you need.
- Treat long-term insomnia with CBT rather than putting up with it.
- If you snore loudly and feel sleepy in the day, get checked for sleep apnoea.
- Watch alcohol, which both disrupts sleep and raises blood pressure.
Keep reading
- Does lack of sleep make you gain weight? Sleep, hunger and appetite
How short sleep changes the hormones that control hunger, how many extra calories tired people eat, and whether sleeping more helps weight loss.
Moderate - Sleep and your immune system: colds, infections and vaccines
How short sleep affects your chance of catching a cold, how well vaccines work, and inflammation in the body, from virus-exposure and vaccine trials.
Moderate - Sleep, memory and concentration: what the research shows
How lack of sleep affects attention, reaction time and memory, why sleep after learning helps memories stick, and what that means for students and drivers.
Strong
Common questions
Can lack of sleep cause high blood pressure?
It probably contributes. In a US study of 4,810 adults followed for 8 to 10 years, people aged 32 to 59 who slept 5 hours or less were about twice as likely to develop high blood pressure, after allowing for other factors. Untreated sleep apnoea is a well-established cause of high blood pressure.
Does sleeping more lower blood pressure?
There is some evidence from small trials that extending sleep in short sleepers lowers blood pressure slightly, but no large trials yet. Treating sleep apnoea with CPAP lowers blood pressure modestly in people who have it.
Is it bad for your heart to sleep too long?
Long sleep, usually 9 hours or more, is linked with more heart disease and stroke in large studies, but this is likely to be mostly because people who are already unwell sleep longer.
References
- Cappuccio FP et al. Sleep duration predicts cardiovascular outcomes: a systematic review and meta-analysis of prospective studies. European Heart Journal, 2011.pubmed.ncbi.nlm.nih.gov
- Gangwisch JE et al. Short sleep duration as a risk factor for hypertension: analyses of the first National Health and Nutrition Examination Survey. Hypertension, 2006.pubmed.ncbi.nlm.nih.gov
- Spiegel K, Leproult R, Van Cauter E. Impact of sleep debt on metabolic and endocrine function. The Lancet, 1999.pubmed.ncbi.nlm.nih.gov
- Irwin MR et al. Sleep disturbance, sleep duration, and inflammation: a systematic review and meta-analysis. Biological Psychiatry, 2016.pubmed.ncbi.nlm.nih.gov
- NICE. Obstructive sleep apnoea/hypopnoea syndrome and obesity hypoventilation syndrome in over 16s (NG202), 2021.nice.org.uk
First published 4 November 2026. Spotted an error? Tell us and we'll correct it. Read our editorial policy.