Thomas Edison changed the world with his invention of the light bulb. Bedtime wasn’t determined by sunset.

But every since we’ve had control of our bedtime, when we go to bed has become more variable and often gets later and later.

A new study suggests that our bedtime may be killing us.

What was the study about?

A new study published in European Heart Journal – Digital Health  investigated if there was a relationship between bedtime and heart disease.

The investigators were curious because as you know, people have built-in biologic internal clocks called circadian rhythm. If we are in the habit of either early or late bedtimes, could bedtime disrupt the body’s internal clock and spell trouble for our health?

How was the study done?

In this study, over 88,000 people in the UK Biobank study were enlisted into the study between 2006 and 2010. The people were on average 61 years of age and 58% were women. The researchers used a tool called an accelerometer and collected information for one week. They also obtained information about lifestyle, health and physical fitness. The investigators then matched all of those people’s bedtimes with who had a new diagnosis of heart disease that included heart attack, heart failure, stroke, heart attack and transient ischemic attack (which is sort of a mild or mini stroke).

What did the study find?

The study followed up the individuals was on average 5.7 years. Of those 88,000+, 3,172 developed heart disease. The highest number of cases were among study participants who went to bed at midnight or later. The lowest incidence was among those who went to be between 10-11:00 pm. Dr. Plans, one of the study researchers speculated that study participants who may stay up very late don’t wake up in time to see morning light, which resets the body’s clock.

The study participants who went to sleep after midnight had a 25% higher risk of developing heart disease than those who went to bed between 10-11:00 pm. Those who went to bed before 10:00 pm had a 24% higher risk. This association between sleep and heart health was stronger for women than men, though the reason why was not clear.

The Bottom Line:

One thing is clear:  Having a bedtime that gets us into bed between 10:00 and 11:00 pm appears to be beneficial to our heart. Earlier and later bedtimes appear harmful to heart health. It’s important to realize in this fast paced world of getting one more thing done before we get to bed, we may be putting ourselves at risk for serious illness. The good news is, our bedtime is something we have control over.