Disruption to a person's internal body clock increases the risk of developing bipolar disorder and depression, scientists say.
A major study of 90,000 people with a disrupted body clock - or circadian rhythm – showed being inactive during the day or active at night could have adverse effects on mental health.
Using mobile phones or making a cup of tea late at night were among bad habits contributing to poor sleeping patterns, researchers said.
Scientists at the University of Glasgow looked at the internal system which controls functions including sleep patterns, body temperature, immune systems and the release of hormones to measure daily rest-activity rhythms, called relative amplitude.
Individuals with lower relative amplitude were found to be at greater risk of several adverse mental health issues, despite researchers considering factors such as age, sex, lifestyle, education and previous childhood trauma.
Daniel Smith, senior author of the paper, told The Times: "But it's not just what you do at night, it's what you do during the day - trying to be active during the day and inactive in darkness.
"Especially in the winter, making sure you get out in the morning in the fresh air is just as important in getting a good night's sleep as not being on your mobile phone."
Dr Laura Lyall, the study's lead author, said the team had found a "robust association" between disruption of circadian rhythms and mood disorders.
"Previous studies have identified associations between disrupted circadian rhythms and poor mental health, but these were on relatively small samples."
Circadian rhythms are variations in physiology and behaviour that recur every 24 hours, such as the sleep-wake cycle and daily patterns of hormone release.
The study, published in The Lancet Psychiatry, found that in addition to increased risk of depression and bipolar disorder.
Lower relative amplitude was also associated with low subjective ratings of happiness and health satisfaction.
Prof Smith, professor of psychiatry and senior author of the study, said: "This is an important study demonstrating a robust association between disrupted circadian rhythmicity and mood disorders.
"The next step will be to identify the mechanisms by which genetic and environmental causes of circadian disruption interact to increase an individual's risk of depression and bipolar disorder.
"This is important globally because more and more people are living in urban environments that are known to increase risk of circadian disruption and, by extension, adverse mental health outcomes."
Additional reporting by Press Association.
