Maintaining a daily rhythm is important for mental health, study suggests

Story highlights

  • People with consistent sleep-wake cycles were less likely to develop major depression and bipolar disorder
  • Those with more disruptions to their circadian rhythms had reduced cognitive functioning in the new study

(CNN)Sticking to a normal daily rhythm -- being active during the day and sleeping at night -- can have more benefits than you might expect.

A new study found that it is linked to improvements in mood and cognitive functioning as well as a decreased likelihood of developing major depression and bipolar disorder.
The study, published Tuesday in the journal The Lancet Psychiatry, looked at disruptions in the circadian rhythms -- or daily sleep-wake cycles -- of over 91,000 adults in the United Kingdom. It measured these disruptions using a device called an accelerometer that is worn on the wrist and measures one's daily activity levels. The participants were taken from the UK Biobank, a large cohort of over half a million UK adults ages 37 to 73.
    The researchers found that individuals with more circadian rhythm disruptions -- defined as increased activity at night, decreased activity during the day or both -- were significantly more likely to have symptoms consistent with bipolar disorder or major depression. They were also more likely to have decreased feelings of well-being and to have reduced cognitive functioning, based on a computer-generated reaction time test.
    For all participants, activity levels were measured over a seven-day period in either 2013 or 2014, and mental health proxies such as mood and cognitive functioning were measured using an online mental health questionnaire that participants filled out in 2016 or 2017.
    "It's widely known that a good night's sleep is a good thing for well-being and health. That's not a big surprise," said Dr. Daniel Smith, professor of psychiatry at the University of Glasgow and a leading author on the study. "But I think what's less well-known and what comes out of this work is that not only is a good night's sleep important, but having a regular rhythm of being active in daylight and inactive in darkness over time is important for mental well-being."