Depression and lack of sleep: Insomniacs 'prone to the mental disorder'

An area of the brain has been identified that can make insomniacs prone to the mental disorder.

The breakthrough could lead to new treatments for both conditions.

A study of college students found those who slept poorly were less likely to have symptoms of depression if these neurons were more active.

For years the idea was you became depressed first, and your sleep got messed up as a consequence.

But evidence is growing sleep problems are a trigger of mental health problems and not merely a symptom.

One problem in proving the link is not everyone who tosses and turns at night becomes depressed and now scientists know why.

Professor Ahmad Hariri, of Duke University in North Carolina, said: “This helps us begin to understand why some people are more likely to experience depression when they have problems with sleep.

“This finding may one day help us identify individuals for whom sleep hygiene may be more effective or more important.“

It is of particular concern in the UK where people are among the most sleep-deprived in the world with almost four-in-ten not getting enough shut eye.

The study published in The Journal of Neuroscience analysed 1,129 university students participating in the Duke Neurogenetics Study.

Brain scans were carried out as they played a card-guessing game which triggered the brain’s ventral striatum (VS), the region sensitive to reward.

It suggested students with higher reward-related VS activity were less likely to report symptoms of depression when experiencing poor sleep quality - which was evaluated by questionnaires.

Professor Hariri said individuals whose brains are more attuned to rewards may be protected from the bad mental health effects of poor sleep.

The VS is a region deep within the brain which helps regulate behaviour, helping reinforce those that are rewarded while reducing those that are not.

Electrical stimulation of the VS has been shown to reduce symptoms of depression in patients who are resistant to other forms of treatment.

Earlier studies by Prof Hariri's team show people with higher reward-related VS activity are more resilient to stress.

Lead author Dr Reut Avinun said: “We've shown reward-related VS activity may act as a buffer against the negative effects of stress on depressive symptoms.

“I was interested in examining whether the same moderating effect would also be seen if we look at sleep disturbances.”

When playing the card game those less susceptible to the effects of poor sleep showed significantly higher VS activity in response to positive feedback.

Professor Hariri said: “Rather than being more or less responsive to the consequences of any actions we are able to more confidently say it is really the response to positive feedback - to doing something right - that seems to be part of this pattern.

“It's almost like this reward system gives you a deeper reserve. Poor sleep is not good but you may have other experiences during your life that are positive.

“And the more responsive you are to those positive experiences the less vulnerable you may be to the depressive effects of poor sleep.”