Night owls, take note: Grandma was right all along about the benefits of an early bedtime, irrespective of your chronotype (the natural inclination of your body to sleep at a certain time).  A new study has upended the traditional belief that aligning sleep schedules with one's natural sleep preference, or chronotype, is the best approach for mental well-being.

The research shows that staying up late is linked to higher rates of mental health disorders, regardless of whether individuals are morning people or night owls. To safeguard mental health, researchers recommend turning off the lights by 1 a.m.

Conducted by Stanford Medicine, the study analysed nearly 74,000 adults and found that the timing of sleep itself plays a critical role in mental health. Surprisingly, the findings highlight that early bedtimes offer significant benefits for everyone, across all chronotypes. Published in Psychiatry Research, the study's senior author, Jamie Zeitzer, a professor of psychiatry and behavioral sciences, remarked, "We found that alignment with your chronotype is not crucial here, and that really it's being up late that is not good for your mental health. The big unknown is why."

Renske Lok, a postdoctoral scholar in psychiatry and behavioural health, led the study, which presented unexpected results. Previous research by Zeitzer's team suggested that women with cancer who did not align their sleep with their chronotype had shorter lifespans. This led to an expectation that aligning sleep schedules with chronotype would be beneficial.

However, the new findings challenge this assumption. The researchers examined middle-aged and older adults in the United Kingdom, gathering data on their sleep habits, including their morning or evening preferences. Participants wore wearable accelerometers for a week to track their sleep patterns, and their mental health status was assessed through health records, covering any mental or behavioural disorder listed in the International Classification of Diseases.

Among the 73,880 participants, 19,065 identified as morning types, 6,844 as evening types, and 47,979 fell somewhere in between. The results were revealing: both morning and evening types who stayed up late exhibited higher rates of mental health disorders, including depression and anxiety.

The study showed that night owls who adhered to their natural late schedules were 20 per cent to 40 per cent more likely to be diagnosed with a mental health disorder compared to those who adopted an early or intermediate sleep schedule. Likewise, evening types who went to bed earlier fared better in terms of mental health, while morning types who went to bed later suffered less severely.

The study also explored whether poor mental health led people to stay up late but found that late-night wakefulness itself was a significant risk factor for developing mental health issues. Harmful behaviours, such as suicidal thoughts, violent crimes, alcohol and drug use, and overeating, are more common at night, further exacerbating mental health risks.

Strategies like getting morning sunlight and maintaining a consistent early routine could help shift sleep patterns, though changing one's chronotype remains difficult. "Biologically speaking, it's very much like a rubber band-you take a day off and you snap back to where your body wants to be," Zeitzer explained.