Good sleep is essential to fending off depression.
A new study has found that regularly snoozing for less than five hours per night raises the risk of suffering from the blues.
Researchers at University College London used health data from over 7,000 people in England to discover genetic variants showing if they were prone to depression or short sleep.
Those who didn't have a tendency to sleep badly due to their genes were over twice as likely to get depression if they slept five hours or less at night.
Experts had previously suspected that bad sleep was a symptom of poor mental health but now think the opposite is also true.
Dr. Odessa Hamilton said: "We determined that short sleep likely precedes depressive symptoms, rather than the other way around."