10-11pm bedtime linked to a healthier heart

Early birds and night owls risk missing solar cues needed to reset their body clock, risking heart health...
13 November 2021


clock surrounded by clouds and moon


New research links a 10-11pm bedtime with a lower risk of heart disease...

Those who doze off between ten and eleven o'clock at night have a lower chance of developing heart disease compared to those who fall asleep earlier or later, according to a new study published in the European Heart Journal.

Conducted by digital healthcare company Huma, the new research analysed UK Biobank data from 88,026 individuals between the ages of 43 and 79 and investigated the link between sleep and heart disease.

The study participants monitored their physical movements using wrist accelerometers. The points at which they stopped moving were used to determine the time at which they nodded off. Participants' profiles also contained information regarding their general health, lifestyle and physical characteristics. The Huma team combed through these data, looking for links between sleep and heart disease. 

The data were adjusted to take into account common heart disease risk factors, such as smoking, body mass index (BMI) and diabetes. Those who fell asleep between 10pm and 11pm each night, the results showed, had a lower risk of heart disease.

But night owls that went to sleep after midnight had a 25% higher chance of developing heart disease, and those in bed asleep before 10pm also showed a similar - 24 per cent - higher heart disease risk.

David Plans, Head of Research at Huma and co-author of the study emphasises that it is an association not causation that they have found. "It’s much more likely that disruption of the circadian [body] clock itself is the problem. If your behaviour disrupts that clock, that is problematic."

Our circadian clock (or body clock) is an internal biochemical system that syncs our bodies with solar time. It needs resetting every day and does so through exposure to sunlight. Those who fall asleep outside the 10-11pm window are more likely to miss the critical time period in which their clock needs resetting with sunlight.

Plans advises, "if you can’t manage to sleep quite within that hour [10-11pm], going to sleep at a reasonable hour and waking up early enough to get some outside time is seriously beneficial to your health."

We are told regularly how important sleep is for our health, but these findings suggest that the number of hours we get is not the full picture. Working to reset our circadian clocks just after waking could be the key to keeping our hearts healthy.


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