Do you go to bed and wake up at the same time each day? If you don’t, you are increasing your chances of suffering from not just bad moods, but also depression, according to a new study.
The sleep patterns of more than 2,000 trainee physicians were analyzed for more than 100 days as part of the research, carried out by the University of Michigan. A smart device on each intern’s wrist tracked their sleep times and other activity, both before and after their internships started.
A typical intern’s routine – or lack of one – involves late bedtimes, early waking times and large changes in sleeping and waking duration, all of which were found to be detrimental to their mood the following day.
Study participants also recorded their mood using an app and completed a patient healthcare assessment every three months. The “before” and “after” internship results were then compared.
The study, published in Nature’s npj Digital Medicine journal, suggests that irregular sleeping and waking times increase the risk of developing depression – and could even be more detrimental to mental health than not getting enough sleep.
The correlation between sleep problems and depression is also flagged in other studies. In one survey of over-40s in the United States, 57% said they found it hard to fall asleep or stay asleep, while 46% said they felt down or depressed.
Global rates of mental health
While the relatively young, educated medical school interns at the University of Michigan – and a study of older US adults – may not be representative of the global population, the results of both studies point to how widespread mental health issues such as depression are.
The UN estimates that one in four people worldwide will experience a mental health condition in their lifetime.
And there are particularly high levels of depression in some countries, according to a global consumer survey by Statista. In Sweden, 46% of respondents said they had experienced mental health issues in the previous 12 months, as did around two-fifths of those surveyed in the US, Brazil and Russia. But it’s important to note that these findings could be influenced by each country’s social acceptance of mental health issues.
Sleep’s impact on physical health
Too little or poor-quality sleep can also reduce immunity to infections like the common cold, according to a separate study.
Not only the sleep patterns but also the sleep efficiency – the percentage of time people were actually asleep while in bed – of 153 adults aged 21-55 were examined over 14 days by scientists from Carnegie Mellon University in Pittsburgh. Study participants were then exposed to a rhinovirus and monitored for symptoms of the common cold.
They found that participants averaging less than seven hours of sleep a night were almost three times more likely to develop a cold than those averaging eight hours. Similarly, participants experiencing 92% sleep efficiency were five-and-a-half times more likely to catch a cold than those with 98% sleep efficiency.
In short, poorer sleep efficiency and shorter sleep duration in the weeks preceding exposure to the rhinovirus were associated with lower resistance to illness.
So the next time you think it’s a good idea to stay up all night and sleep all day, it may be a better idea to think again.
Johnny Wood, Writer, Formative Content
This article was originally published on World Economic Forum. You can view it here.
Also read: Now sleeping longer than 6.5 hours a night associated with cognitive decline