A new global study has revealed that maintaining sleep regularity is critical to prevent many diseases including liver cirrhosis and gangrene, indicating that the definition of good sleep should include regularity and not just duration. The study also found that sleeping more than 9 hours is not harmful to health contrary to the earlier perception.
The study recently published in Health Data Science, found a link between sleep traits and 172 diseases. The research, led by teams from Peking University and Army Medical University, analysed objective sleep data from 88,461 adults in the UK Biobank, and concluded that sleep regularity — such as bedtime consistency and circadian rhythm stability — are crucial unrecognised factors in disease risk.
The researchers identified that 92 diseases had over 20% of their risk attributable to poor sleep behaviour. Notably, irregular bedtime (after 00:30) was linked to a 2.57-fold higher risk of liver cirrhosis, while low inter-daily stability increased the risk of gangrene by 2.61 times.
The study also challenges previous claims that long sleep of more than 9 hours is harmful. While subjective reports have linked long sleep to stroke and heart disease, objective data revealed this association in only one disease. The researchers found that 21.67% of “long sleepers” actually slept less than 6 hours, suggesting that time spent in bed is often confused with actual sleep time.
Prof. Shengfeng Wang, senior author of the study, said the findings emphasise the significance of sleep regularity and it was time to redefine and broaden the definition of good sleep beyond just duration.
