Missing out on a good night's sleep can leave you more likely to become depressed or suffer from bipolar disorder, research has found. The largest study of its kind put movement monitors on 91,000 people to track activity levels and survey levels of happiness.
The findings, published in the journal Lancet Psychiatry, show being too active at night and inactive in the day was linked to lower mood. Depression and bipolar disorder were more likely over a lifetime. Sleep patterns associated with shift workers and university students were linked with mood instability, unhappiness and loneliness.
Scientists believe this is linked to a disruption of our natural body clock, called the circadian rhythm. Dr Laura Lyall from the University of Glasgow, said: "Our findings indicate an association between altered daily circadian rhythms and mood disorders and wellbeing.
"However, these are observational associations and cannot tell us whether mood disorders and reduced wellbeing cause disturbed rest-activity patterns, or whether disturbed circadian rhythmicity makes people vulnerable to mood disorders and poorer wellbeing." The circadian rhythm of all animals affect bodily functions from temperature regulation to eating habits.
Previous research has shown disrupting this body clock has been linked to higher chance of diseases of the brain and pancreas. Other small studies have suggested a link between sleep patterns and mental health.
The movement of 91,105 participants aged 37 to 73 from the UK Biobank register was measured for seven days each between 2013 and 2015. Mental health questionnaires were then used to assess symptoms of mental disorders. Researchers used computer modelling to try to discount other factors such as age, sex, weight and childhood trauma.
Dr Lyall measuring sleep patterns could be a way for the NHS to target those at risk of developing mental illnesses. She added: "It will be useful for future studies to track participants' rest-activity patterns over time to see whether disturbed rhythms can predict whether someone is more likely to go on to develop a mood disorder."