With our action-packed lives, nearly a third of Americans struggle with getting too little sleep. However, some studies suggest getting too much sleep may actually be just as problematic as not getting enoughTotal daily sleep duration and the risk of dementia: a prospective population-based study. Benito-León, J., Bermejo-Pareja, F., Vega, S., et al. Department of Neurology, University Hospital ’12 de Octubre’, Madrid, Spain. European Journal of Neurolology 2009 Sep;16(9):990-7. Epub 2009 Mar 31.! So how much is too much sleep?

We Sleep All, Sleep All Day—Why It Matters

Medical experts typically recommend seven to nine hours of shuteye per night for adults, and even more for kids. (Yikes, no wonder first period in high school was always so tough.) But everyone needs a different amount of sleep, and research suggests our sleep habits are influenced by environmental factors (like exposure to light) and genetic traitsIndividual traits and environmental factors influencing sleep timing: a study of 225 Japanese couples. Hida, A., Kitamura, S., Enomoto, M., et al. Department of Psychophysiology, National Institute of Mental Health, National Center of Neurology and Psychiatry, Tokyo, Japan. Chronobiology International 2012 Mar;29(2):220-6.Life between clocks: daily temporal patterns of human chronotype. Roenneberg, T., Wirz-Justice, A., Merrow, M. Center for Chronobiology, Institute for Chronobiology, Munich, Germany. Journal of Biological Rhythms 2003;18(1):80-90.. Not getting enough sleep on a regular basis can contribute to a condition known as “sleep drunkenness,” which leads to feeling groggy and disoriented. But we weren’t dreaming when we felt more tired after snoozing longer than usual—sleep drunkenness can happen when we get too little sleep and too much sleep. In both cases, sleeping more or less than usual can upset the body’s circadian rhythms, which regulate sleep cycles. Getting too much sleep may be about more than just running to make the train in the morning. Like sleeping too little, oversleeping has also been linked to some serious health problems. Research suggests sleeping more than eight or less than seven hours per night is associated with an increased risk of obesity, diabetes, high blood pressure, and heart diseaseShort and long sleep are positively associated with obesity, diabetes, hypertension, and cardiovascular disease among adults in the United States. Buxton, O.M., Marcelli, E. Brigham and Women’s Hospital, Department of Medicine, Harvard Medical School, Division of Sleep Medicine, Boston, MA. Social Science & Medicine 2010;71(5):1027-36.Sleep duration and cardiometabolic risk: a review of the epidemiologic evidence. Knutson, K.L. Section of Pulmonary/Critical Care, Department of Medicine, University of Chicago, Chicago, IL. Best Practice & Research: Clinical Endocrinology & Metabolism 2010;24(5):731-43.. Those who sleep less than five or more than six hours per night also show an increased risk of mortalityMortality related to actigraphic long and short sleep. Kripke DF, Langer RD, Elliott JA, Klauber MR, Rex KM. Department of Psychiatry, University of California, San Diego, La Jolla, CA. Sleep Med. 2011 Jan;12(1):28-33. Epub 2010 Sep 25.. And one study found people who slept for more than nine or less than seven hours a night were about twice as likely to develop dementia as those who typically slept for seven hoursTotal daily sleep duration and the risk of dementia: a prospective population-based study. Benito-León, J., Bermejo-Pareja, F., Vega, S., et al. Department of Neurology, University Hospital ’12 de Octubre’, Madrid, Spain. European Journal of Neurolology 2009 Sep;16(9):990-7. Epub 2009 Mar 31.. Pulling a Sleeping Beauty is often a sign of a medical condition called “hypersomnia,” or excessive sleepiness. Hypersomnia can result from a range of factors, from central nervous system injuries to common over-the-counter medications. In certain cases, alcohol abuse can alter sleep cycles because booze prevents chemical interactions that take place during deeper stages of sleep. Oversleeping can also be part of the cycle of depression; people sleep more than usual because they feel depressed and continue to feel blue because they spend so much time sleeping. Whether we have someone to snuggle with influences how much we sleep, too; single people may be more likely to sleep in (longer than 8.5 hours) than their pals in relationships. But getting the right amount of sleep may not be as simple as setting an alarm clock.

Let Me Sleep On It—The Answer/Debate

Unfortunately, it’s not so easy to figure out the ideal amount of sleep for everyone. To find the right amount of rest, it might be necessary to experiment. Lame as it may seem, start setting an earlier bedtime than usual until it’s possible to wake up without an alarm clock. (It’s probably best to start these tests on a “sleep vacation” or a weekend to avoid missing the morning office meeting.) Once you start sleeping about the same amount every night, you’ve figured out how much rest you need on a regular basis. It may also be worth keeping a sleep diary with sleeping hours, daily alertness, and other stats like coffee breaks and workouts (e.g. drinking three late-afternoon frappuccinos might be important to note). Keep in mind that not sleeping enough can have some scary consequences, too: Going 24 hours without any sleep can impair functioning just as much as a blood alcohol level of 0.1 percentSleep deficit: the performance killer. A conversation with Harvard Medical School Professor Charles A. Czeisler. Czeisler, C.A. Harvard Medical School, USA. Harvard Business Review 2006 Oct;84(10):53-9, 148.! Sleep debt can also mask an individual’s basic sleep needs—so if it’s been busy season with all-nighters, wait until it’s been a week or two of normal sleeping before trying to note any patterns. Until sleep debt is paid back, it’s fine to sleep longer than usual; one study found that just one 10-hour sleep session significantly improved cognitive function following five nights of sleep deprivationNeurobehavioral dynamics following chronic sleep restriction: dose-response effects of one night for recovery. Banks, S., Van Dongen, H.P., Maislin, G., et al. Division of Sleep and Chronobiology, Department of Psychiatry, University of Pennsylvania School of Medicine, Philadelphia, PA. Sleep 2010 Aug;33(8):1013-26.. If it’s still tough to wake up in the morning despite consistently getting at least seven hours of sleep a night, it may be wise to see a doctor. Sleeping too much (or too little) can have serious consequences for health and well-being and can also be symptomatic of other medical issues. Figure out the cause of the change in sleep habits, and then start counting those sheep.

The Takeaway

Everyone needs a different amount of sleep that depends on genetic and environmental factors. “Sleep drunkenness” can happen when we sleep too little or too much, and too much sleep is linked to an increased risk of obesity, diabetes, and other health issues. Oversleeping can be a sign of hypersomnia, which can sometimes result from popping over-the-counter painkillers. At the same time, sleep deprivation can have serious consequences, too.