In 2007, a study in Finland found that people who slept more than eight hours faced increased mortality risks, to the tune of about 20 percent. Similarly, a study conducted in Britain found that people who slept five hours or fewer and those who slept more than eight hours also faced increased risks. Yet another study showed that people who habitually slept more than eight hours had an increased chance of stroke relative to others with less sleep. So what gives?
Scientists admit that sleep and longevity are somehow associated; however, they maintain that there might be confounding factors. “We don’t know if it’s the long sleep. It could be something else causing illness and the long sleep,” said Dr. Daniel Kripke, co-director of Scripps Clinic Sleep Center in La Jolla, California, who has researched the topic for 35 years.
People who suffer from habitually excessive sleep, aka hypersomnia, may be experiencing poor quality sleep. Despite sleeping the recommended eight hours, a person could still feel exhausted because of poor quality sleep. “Oftentimes, we only think of sleep in terms of minutes — but that’s really the quantity of sleep. In fact, there’s a quality of sleep,” said Breus, author of the book “Beauty Sleep.”
The average sleep cycle takes about ninety minutes to finish. It commences with stage 1, where sleep in the lightest, and continues on to deeper levels through stage 4. Finally, sleep transitions to rapid eye movement (REM) sleep, which is when the person experiences dreams. “When you have poor quality sleep, you spend a lot of time in stage 1 sleep,” said Shives, a spokesperson for the American Academy of Sleep Medicine. “You will tend to want to sleep longer to make up for the quality and increasing quantity.”
Michael Breus, the clinical director of the sleep division at Southwest Spine and Sports in Scottsdale, Arizona notes that if you notice a pattern of extended sleep, measured as more than nine hours consistently, you need to engage your physician to get to the root cause. Poor quality sleep may be brought about by sleep apnea, narcolepsy or some form of restless leg syndrome.
Ultimately, some people are just fine on little sleep, and others require a bit longer. Researchers think that there is a genetic reason behind the inconsistency. Though it is early in the game, University of California, San Francisco (UCSF) scientists believe they have discovered a gene, hDEC2, which regulates sleep length, and that would explain why some require more while others require less. Hopefully, the UCSF scientist will also be able to build up the Finnish and British studies of 2007 and put to the rest the question of whether lengthy sleep is in fact bad for your health.