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One in four people with depression could have ‘circadian depression’, in which disruptions to the body’s internal clock contribute to a person’s mental illness, according to a large population and genetics study 1 published today in the British Journal of Psychiatry .

The study found that people with circadian depression, which is characterized by disrupted sleep, low energy and reduced physical activity during the day, tended to have more severe symptoms that start at a younger age than those with other forms of depression.…