Can chronically poor sleep cause me to have a stroke at a younger age?

Both too little and too much sleep are associated with an increased risk of stroke. The most striking figure comes from research into long sleep: people who consistently sleep more than average have a 46% higher chance of having a stroke compared with people who sleep a normal duration. That is a remarkably high number, but there is an important caveat: sleeping long can also be an early sign of an underlying condition, rather than the cause itself.

For people who chronically sleep too little, the picture is more nuanced. An analysis of more than five million people showed that short sleepers had a 16% higher chance of cardiovascular disease overall. Stroke separately was not calculated in isolation in that study, so the specific stroke risk associated with too little sleep is less clearly defined. Nevertheless, there is no reason to dismiss it: short sleep duration fits into a pattern of elevated cardiovascular risk.

Working shift work, in which sleep deprivation occurs structurally, shows a slightly elevated stroke risk of 5%. That sounds modest, but the studies partly contradict one another and it is not clear whether the sleep deprivation itself is the culprit or other aspects of irregular working patterns, such as stress or lifestyle.

All associations were found in large observational studies, not in experiments in which sleep was deliberately manipulated. That means no definitive cause-and-effect conclusion can be drawn from them. However, the pattern across multiple large studies does provide grounds for taking chronic sleep deprivation seriously as part of your cardiovascular health.