Too Much Sleep May Actually Decrease Your Lifespan

Researchers have been studying mortality rates for centuries in an effort to determine the best practices to achieve a long and healthy life. For more than three decades, they've known that prolonged lack of sleep is one of the many habits that make you more likely to die early — largely based on a 1989 rat study by Chicago-based researchers, which was published in the journal Sleep. Continued research, though, has found that sleeping too much has similar risks.

In a collaborative effort, University College London and University of Warwick researchers studied the effects of sleep patterns on more than 10,300 people at two points in their lives: from 1985 to 1988 and again from 1992 to 1993 if those participants were still alive. After adjusting for factors including (but not limited to) age, employment grade, and alcohol use, the scientists presented to the British Sleep Society in 2007 that sleeping eight hours or more doubles the mortality risk from all causes.

The greater risk of early death from oversleeping was substantiated by researchers at Keele University in a 2018 study published in the Journal of the American Heart Association. While examining the link between sleep, cardiovascular disease, and mortality in more than 3 million people, the scientists concluded that sleeping for 10 hours or more per night leads to a 30% higher risk of dying compared to getting just seven hours. They also found that the participants were 56% and 49% more likely to die from a stroke and cardiovascular disease, respectively.

By definition, oversleeping means that you sleep more than nine hours in a day. There are many reasons why people may sleep too much. Sleep apnea, insomnia, narcolepsy, and other sleep disorders are the most obvious culprits. However, other health conditions — anxiety and depression, cardiovascular disease, chronic pain, diabetes, obesity, and more — can have an impact on excessive sleeping. Unfortunately, prolonged oversleeping can increase inflammation, cause chronic diseases, and hinder the immune system, one of the most important systems in the body. The fortunate side is that many of these conditions are treatable or manageable so that better sleep patterns are easier to maintain. Plus, with regular sleep and certain conditioning, it's possible to edit bad memories.

So, how much sleep do you really need? According to the Centers for Disease Control and Prevention, the daily recommended amount of sleep that people should get depends on their ages. Children and teens need to sleep longer because sleep is when brain development and growth occur. For adults between 18 and 60 years old, though, seven hours is the recommended amount. Meanwhile, those aged 61 to 64 shouldn't sleep more than nine hours, and those aged 65 and older shouldn't sleep more than eight hours. These are general recommendations, though; some people feel their best with fewer or more hours. That's because sleep quality is more important, and a study published in 2024 in Sleep found that it's a stronger mortality risk predictor than the number of hours.