What's much more interesting is that she found that it's sleep quality that is more important for maintaining good mental health than the amount of sleep.
“This is surprising because sleep recommendations predominantly focus on quantity rather than quality,” Wickham says. “While we did see that both too little sleep - less than eight hours - and too much sleep - more than 12 hours - were associated with higher depressive symptoms… sleep quality significantly outranked sleep quantity in predicting mental health and well-being.”
The study was carried out on more than 1000 adults, aged 18 to 25 who were asked about how much they slept and how well they slept, as well as information about exercise and dietary habits. They were then asked to complete a questionnaire to gauge their mental health including whether they felt depressed or positive
Sleep quality and quantity were found to be the strongest lifestyle predictors of depression, that is people who had better sleep quality, and those who slept inside the range of eight to 12 hours per night reported fewer symptoms of depression. Overall though it was sleep quality that “significantly outranked” other health behaviours linked to mental health and well-being.
A separate study from the University of California, Berkeley also found that just one sleepless night can trigger up to a 30% rise in anxiety levels.
So good sleep is a key factor in your mental well-being but it's quality, not quantity that we should be focusing on.