Inadequate sleep, clocking fewer than five hours per night, may heighten the susceptibility to experiencing symptoms of depression, according to recent research findings. While the association between poor sleep and mental health issues has been acknowledged, discerning the causal relationship has been an enduring enigma. Scientists have now unveiled compelling evidence suggesting that consistent short-duration sleep precedes the onset of depressive symptoms.
PhD candidate Odessa Hamilton, the lead author of the study from UCL, elucidated the research’s significance, stating, “We have grappled with the conundrum of whether suboptimal sleep duration or depression initiates the vicious cycle. Although they frequently coincide, our employment of genetic susceptibility to disease has led us to infer that inadequate sleep likely precedes the emergence of depressive symptoms, rather than the contrary.”
The study delved into the genetic and health records of 7,146 participants enrolled in the English Longitudinal Study of Ageing (ELSA). Both sleep duration and depression exhibit hereditary components, with earlier investigations disclosing a heritability rate of approximately 35% for depression and genetic variations contributing to 40% of the variance in sleep duration.
Over a span of four to twelve years, researchers tracked the study’s subjects, ultimately revealing that individuals with a genetic inclination towards brief sleep durations (less than five hours per night) were at a heightened risk of developing depressive symptoms. Conversely, those genetically predisposed to depression did not exhibit an elevated risk of sleep-related issues.
In the study cohort, participants averaged seven hours of sleep per night. The percentage of individuals sleeping for less than five hours at the study’s outset increased from just over 10% to more than 15% by the study’s conclusion. Simultaneously, the proportion of participants manifesting depressive symptoms rose from around 9% to 11%.
The data showed that individuals with less than five hours of sleep were 2.5 times more likely to develop depressive symptoms, while those already experiencing depressive symptoms had a one-third greater chance of encountering short sleep durations.
While these findings may present a daunting prospect for individuals grappling with sleep disturbances, Hamilton emphasized that neither poor sleep nor depression should be perceived as inescapable destinies. She underscored the importance of prioritizing sleep for the preservation of mental well-being, advising, “My recommendation is to give precedence to sleep and shun procrastination in this regard. Genetics may load the gun, but the environment pulls the trigger. You might be genetically predisposed, but you can take proactive measures to mitigate the risk.”
These revelatory findings have been disseminated in the journal Nature Translational Psychiatry, underscoring the critical role of sleep in promoting mental health.