Short Sleep, Long Depression: Which Comes First?

Insufficient Sleep Linked to Higher Risk of Depression

News Picture: Short Sleepers May Be at Higher Risk for Depression

Short sleep = higher risk of depression

By Cara Murez, HealthDay Reporter

Scientists have always wondered about the relationship between sleep and depression. Does depression lead to less sleep or is it the lack of sleep that triggers depression? A recent study suggests that it’s the latter. Getting less than five hours of sleep a night may increase the risk of developing depressive symptoms. As lead author Odessa Hamilton puts it, “We have this chicken or egg scenario between suboptimal sleep duration and depression, but which comes first is largely unresolved.” So, let’s dive into the intriguing findings!

The Genetics of Sleep and Depression

Both sleep style and depression have genetic components. Previous twin studies have indicated that depression is about 35% genetic, and these inherited differences also account for 40% of the variance in sleep duration. To explore this further, the researchers analyzed genetic and health data from over 7,000 people with an average age of 65.

Sleep Duration Precedes Depressive Symptoms

The results showed that those with a stronger genetic predisposition to short sleep were more likely to develop depressive symptoms over four to 12 years. Surprisingly, people with a greater genetic predisposition to depression did not have an increased likelihood of short sleep. This suggests that sleep duration precedes depressive symptoms, rather than the other way around.

So, How much Sleep is Too Little?

According to the study, people sleeping five hours or less were 2.5 times more likely to develop depressive symptoms. On the other hand, sleeping long, more than nine hours a night, was also linked to developing depressive symptoms, with individuals who slept long being 1.5 times more likely to experience these symptoms compared to those who slept an average of seven hours. However, depressive symptoms were not associated with sleeping longer.

A Wake-Up Call for Future Research

The study’s senior author, Dr. Olesya Ajnakina, underscores the importance of genetic propensity in understanding sleep duration and depressive symptoms. The researchers used findings from previous genome-wide association studies, which identified thousands of genetic variants linked to a higher risk of depression and short or long sleep. Additionally, they examined non-genetic associations between depressive symptoms and sleep duration to ensure the study’s robustness.

The Connection Between Sleep, Depression, and Aging

As we age, both suboptimal sleep and depression become more common. With the global population aging rapidly, it is crucial to understand the mechanism that connects depression and a lack of sleep. This study lays the groundwork for future investigations into the intersection of genetics, sleep, and depressive symptoms.

So, next time you find yourself tossing and turning in bed or staying under the covers longer than usual, remember that your sleep habits may have a role to play in your mental well-being. Sweet dreams, everyone!

Source: University College London, news release.


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