Is Oversleeping Bad for Your Health?

The effects of sleep deprivation and how it can affect our health in multiple areas including cognition, physiological, and physical is an extensively studied subject. But according to studies both short sleep, which is considered to be less than 6 hours, and long sleep, more than 8 hours can cause unfavorable health outcomes. 

What is Oversleeping? 

Even today after all the research that is available it is still largely unknown the appropriate time that an adult should sleep. Most studies recommend around 6 to 8 hours of sleep for adults of 18 to 64 years. 

In the majority of studies less than six hours is considered undersleeping, while more than nine hours is considered to be excessive or oversleeping.

Longer sleep habits have been associated with depression, cognitive impairment, increased pain, inflammation, and risk of chronic health conditions, even an increased risk of mortality.

What Do Studies Say? 

Cognitive Function

In a study published in the Journal of Sleep Research, researchers investigated the relationship between self-reported sleep factors (duration, insomnia, use of sleeping medicine, fatigue feelings and tiredness) with cognitive function in a total of 5,177 people aged 30 years or older. 

The researchers found that in a general adult population, sleep-related factors (short and long sleep duration, and tiredness) were independent predictors of low objectively measured cognitive functioning, even after control of other factors. They found that both sleep deprivation and long sleep duration have a negative effect on cognitive function.

Increased Levels of Inflammation

Evidence of a pro-inflammatory role for sleep loss, and the consequential cardiovascular outcomes are being discovered. Sleep deprivation studies have shown an association between sleep loss and pro-inflammatory processes that promote the development of atherosclerotic plaques.

C-reactive protein (CRP) is a systemic marker of chronic inflammation and is associated with sleep duration. Studies have found that short and/ór long (extreme) sleep durations are associated with elevated CRP.

In a study published in the journal Sleep, researchers evaluated extremes of sleep duration with the levels of CRP. They used self-reported sleep time (TST) from participants that responded to the 2007-2008 National Health and Nutrition Examination Survey (NHANES), a national survey conducted by the CDC. 

The researchers found that CRP was elevated among long sleepers (>9 hours), even after adjusting for demographics, socioeconomic, BMI, insomnia, sleep apnea, smoking, alcohol use, medications and comorbidities. CRP was also elevated in very short sleepers (<5 hours), but it was often not significant in models adjusting for sleep and comorbidities.

Memory Impairment

In a study published in the journal Sleep, researchers examined the association between sleep-related factors and memory impairment. 

The study included 28,670 participants aged 50 to 85 years from a community in Guangzhou, China. The researchers found that short and long duration sleep was an important sleep-related factor independently associated with memory impairment and that it may be a useful marker for increased risk of cognitive impairment in older people. 

Mortality 

According to information from the American Cancer Society, women, and men self-reporting <4 hours of sleep are 1.48 and 2.80 times as likely to have died within 6 years compared to those reporting 7-7.9 hours of sleep. 

Sources:

Hilda Aliouche, B.Sc. (2022, Jan 11). The Health Risks of Oversleeping. News Medical Life Sciences. Retrieved from:
https://www.news-medical.net/health/The-Health-Risks-of-Oversleeping.aspx 

Kronholm E, Sallinen M, Suutama T, Sulkava R, Era P, Partonen T. Self-reported sleep duration and cognitive functioning in the general population. J Sleep Res. 2009 Dec;18(4):436-46. doi: 10.1111/j.1365-2869.2009.00765.x. Epub 2009 Aug 31. PMID: 19732318.

Grandner MA, Buxton OM, Jackson N, Sands-Lincoln M, Pandey A, Jean-Louis G. Extreme sleep durations and increased C-reactive protein: effects of sex and ethnoracial group. Sleep. 2013;36(5):769-779E. Published 2013 May 1. doi:10.5665/sleep.2646 

Xu L, Jiang CQ, Lam TH, et al. Short or long sleep duration is associated with memory impairment in older Chinese: the Guangzhou Biobank Cohort Study. Sleep. 2011;34(5):575-580. Published 2011 May 1. doi:10.1093/sleep/34.5.575

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https://www.hopkinsmedicine.org/health/wellness-and-prevention/oversleeping-bad-for-your-health