A new study from the University of Cambridge (UK) has found a J-shaped relationship between sleep duration and stroke risk..

This means that prolonged sleep (more than 8 hours per night) is associated with an increased risk of stroke, and the more hours a person sleeps per day, the higher the risk..

At the same time, insufficient sleep (less than 6 hours) leads to an increase in the risk of stroke by 18%, and long sleep - by as much as 46%, even taking into account such factors as the presence of cardiovascular disease..

If a person reports that he always slept for a long time, then his individual risk of stroke is 2 times higher compared to those who sleep 7-8 hours a day. But if a person changed his habit and began to sleep longer only within the last four years, then the risk of a stroke turned out to be as much as 4 times higher..

Dr. Yue Leng, lead author of the study, told Medscape Medical News: “We are confident that the results are correct.. Long sleep is associated with an increased risk of stroke. Our study does not suggest that sleep causes stroke, but it may be a useful marker for identifying diseases and conditions that lead to stroke.. The doctor should simply ask his patient how long he sleeps and how his regimen has changed over the past few years, and the answer received will provide valuable information about the risk of stroke..

The results of Dr. Leng's study were published at the end of February in the journal Neurology..

Changes in sleep patterns are cause for concern.

British scientists analyzed data from the European Prospective Investigation of Cancer-Norfolk (EPIC Norfolk) study. The EPIC-Norfolk study was funded by the UK Medical Research Council and Cancer Research UK..

The analysis included 9,692 participants who completed a sleep questionnaire in 1998-2000 and again in 2002 and 2004. None of them had a history of stroke before the start of the study.. The scientists followed the participants until 2009..

During 9.5 years of follow-up, 346 strokes were registered. Long sleep (more than 8 hours per night) was associated with an increased risk of stroke: OR 1.46 (95% CI 1.08-1.98). The result remained significant after adding other significant factors, including the presence of cardiovascular disease.

For insufficient sleep duration (less than 6 hours per night), the relationship was not statistically significant: OR 1.18 (95% CI 0.91-1.53). Subgroup analyzes showed that insufficient sleep was more strongly associated with stroke in younger people, and prolonged sleep was more strongly associated with older adults..

An additional meta-analysis using the Ovid Medline, EMBASE and Cochrane databases showed almost the same results.. For long sleep, the odds ratio was 1.45 (95% CI 1.30–1.62), and for insufficient sleep, the OR was 1.15 (95% CI 1.07–1.24).

There is no causal relationship?

Author of an article in Neurology, Dr. Alberto Ramos, director of the UHealth Sleep Medicine Program at the University of Miami's Miller School of Medicine, writes that there may not be a causal relationship between sleep duration and stroke risk..

“There are already several studies that show some kind of relationship between sleep duration and stroke.. The big question is why. Excess sleep is a mechanism that increases the risk of stroke? Or excess sleep is just a marker of some other disease that makes a person sleep more and cause strokes.? I think the latter is more likely,"

As an example, Dr.

Ramos cites sleep apnea, a condition in which people sleep longer to compensate for the disruption in sleep quality due to apnea.. This condition is a proven risk factor for stroke..

Be that as it may, Ramos considers the results of the latest study very important and useful.. He says doctors should look first for sudden changes in sleep patterns..

“If the patient used to sleep 5-7 hours a day, and now 9-10 hours, this is a reason to suspect something is wrong and examine him,” he says..

medbe. en.