Insufficient sleep damages the brain, increasing the risk of stroke and depression

Research conducted at University College London suggests that insufficient sleep is harmful to the brain and increases the risk of both stroke and depression.

Researchers from the University of Alabama in Birmingham assert that people who habitually sleep less than six hours per day significantly increase their risk of having a stroke. This underlines the potential dangers posed to the brain by inadequate sleep.

Historically, disturbed sleep was regarded as merely a symptom of poor mental health. However, recent studies have revealed a more complex relationship between sleep and mental well-being.

"We are dealing with a chicken or egg dilemma between insufficient sleep and depression. Both conditions often co-exist, but which comes first? This remains largely unresolved. We found that sleep disturbances are likely to precede depressive symptoms, not vice versa," clarified Odessa S. Hamilton, the lead author of the study.

Researchers at University College London analyzed genetic and health data from 7,146 people in the United Kingdom. They were able to identify genetic variations that indicated participants' susceptibility to depression and sleep deprivation.

Both sleep duration and depression are to some extent inheritable. Current research suggests the inheritability of depression is around 35%, while sleep duration has about a 40% genetic component.

UCL's researchers have detected that among individuals with a stronger genetic predisposition to sleep deprivation (less than five hours per night), there's an increased risk of developing depressive symptoms over the next four to twelve years, compared to those who sleep longer. Conversely, those with a greater genetic predisposition for depression do not exhibit a significantly higher chance of sleep deprivation.

The researchers concluded that, among individuals sleeping five hours or less per night, the risk of depressive symptoms is 2.5 times greater. However, for those presenting depressive symptoms, the risk of sleep deprivation only increases by one-third.

The researchers also identified a connection between long sleep duration and the manifestation of depressive symptoms. For participants who regularly sleep more than nine hours, the risk of developing depressive symptoms was 1.5 times greater than for those who average seven hours of sleep.