Going to bed after midnight could be having a detrimental effect on your health, new study warns

It's fairly well documented that how much sleep you have can have a profound impact on both your physical and mental health, but when you sleep could actually be just as important, a new study has found.

A recent review, which tracked the sleep habits of more 88,000 adults all over the world, assessed the link between poor sleep habits and a higher risk for several diseases, and the results could completely transform what we define as good sleep.

Researchers from Peking University and Army Medical University analysed data over an average of 6.8 years and found 92 different diseases that had more than 20 percent of their risk attributed to poor sleep behaviours, such as irregular bed and wake times.

The research, published in Health Data Science, highlighted the importance of sleep regularity in maintaining a stable circadian rhythm, and it's bad news for people who regularly stay up past midnight.

Staying up later than 12.30am is linked with increased risk of liver cirrhosis. (Getty Stock Images)

In fact, people who regularly stay up later than 12.30am were found to have 2.57x more risk of developing liver cirrhosis; a condition where the liver becomes severely scarred due to long-term damage. People with low interdaily stability had a 6.61-fold higher risk of developing gangrene.

It is important to note, however, that the results show correlation, not causation. For example, liver cirrhosis can be caused by lifestyle choices such as high alcohol consumption, so a connection could be made between staying up past 12.30am and drinking excessively.

Interestingly, the study also fond there was no harm associated with long sleep, defined as more than nine hours per night, following previous claims linking long sleep with stroke and heart disease risks.

The timing of sleep appears just as important as the length. (Getty Stock Images)

One potential explanation for the now disputed claim could be down to people in previous studies misreporting their sleep time, as it was found that around one in five people who claimed to sleep nine hours actually slept less than six, confusing time in bed with time asleep.

The main takeaway, the team summised, was the importance of healthy sleep habits and maintaining circadian rhythm to protect against the risk of the 92 diseases associated with poor sleep, in addition to the known importance of getting a good quantity of sleep too.

Senior author of the study, Professor Shengfeng Wang concluded: "Our findings underscore the overlooked importance of sleep regularity. It's time we broaden our definition of good sleep beyond just duration."