From concentration and mood to energy levels and heart health, getting the right amount and quality of sleep helps maintain good physical and emotional health. Now, researchers from Stanford University have further supported this with a study that establishes a link between late bedtimes and poor mental health.
Do you need to follow your own chronotype – i.e. biological rhythm – to stay in good health? That’s the question they set out to answer, analysing data from 73,888 adults aged 63.5, on average.
These volunteers were asked to provide information about their sleep and, in particular, about their inclination to sleep at specific times. They were also asked to use a wearable monitor to track their slumber for seven days, so the scientists could see how their chronotype aligned with their behaviour.
The experts noted that over 19,000 participants declared themselves to be morning people, while over 6,800 had a late chronotype. But the vast majority, almost 48,000 participants, were of “intermediate” chronotype, falling somewhere in the middle.
The sleep data collected was coupled with data from medical records concerning the participants’ mental health. Published in the journal Psychiatry Research, the results suggest that late bedtimes, regardless of individual preferences, are associated with higher rates of mental and behavioral disorders.
In a news release, the researchers said they were surprised to find that “aligning with one’s chronotype was not the best choice for everyone’s mental health; it was better, in fact, for night owls to lead a misaligned life” – that is, for them NOT to follow their natural biological rhythm.
The scientists even tried to disprove this, to no avail: “The results were clear – both morning and night types who went to sleep late had higher rates of mental health disorders, including depression and anxiety,” they outlined.
Their findings point to a particularly increased risk of mental health disorders among participants who habitually went to bed late and then got up late. The latter were 20-40% more likely to be diagnosed with a mental health disorder than those who got up early (or not too late).
To verify their findings, the researchers looked at sleep duration or consistency of sleep timing, but these failed to explain the differences in mental health observed between participants.
While they are aware it can be difficult to go against chronotype, the experts thus recommend going to bed before 1am to preserve mental health. They do not explain the mechanism behind this association, but suggest it might be owing to the poor decisions one is more likely to make late at night.
“Many harmful behaviours are more common at night, including suicidal thinking, violent crimes, alcohol and drug use, and overeating,” the study news release concluded.
“One theory, known as the ‘mind after midnight’ hypothesis, suggests that neurological and physiological changes late at night can foster impulsivity, negative mood, impaired judgement, and more risk-taking.”