How does sleeping too much harm your health?
Getting enough sleep every day is the best medicine for cognitive, physiological and physical health. Therefore, sleeping too much or too little can have certain negative effects on health.
Depending on age and living environment, there will be corresponding hours of sleep. However, the US National Sleep Foundation recommends that adults, aged 18-64, sleep 7-9 hours per day is normal. Sleeping less than 6 hours/day is short sleep and more than 9 hours/day is too much sleep.
How does sleeping too much affect health?
Sleeping too much and symptomsamnesia
In a population-based study conducted in Spain, prolonged sleep duration and excessive sleep were found to be associated with an increased risk of dementia.
Accordingly, baseline information on sleep duration of more than 3 thousand participants was collected in the study; the average follow-up period was 3.2 years, during which 140 cases of dementia were identified.
Impact on mental health
In a British study, people who slept too much (more than 8 hours/day) had more symptoms of depression than those who slept normally. This finding has been repeated through several surveys and meta-analyses showing that the rate of depression is higher in people who sleep too much than those who sleep enough hours.
More recently, another study has also demonstrated a strong link between excessive sleep duration and chronic depression/anxiety.

Too much sleep and signs of chronic inflammation
C-reactive protein (CRP) is a marker of chronic inflammation. This biomarker has been linked to sleep duration. Laboratory studies have shown that elevated CRP is found in cases of excessive sleep duration.

Although the link between obesity and too much sleep is not yet firmly established, an analysis of more than 56,000 participants in the US National Health Survey found an association between long sleep (>8 hours) and obesity, diabetes, cardiovascular risk, and hypertension.
Risk of heart disease
Data from the National Health and Nutrition Examination Survey (NAHNES) show that sleep duration is a risk factor for cardiovascular disease. In this study, researchers found that both short and long sleep duration were associated with a higher risk of coronary heart disease and stroke. Participants who slept more than 8 hours per night had double the risk of angina and a 10% higher risk of coronary heart disease than those who slept normally.
Furthermore, another analysis in the US showed that the mortality rate due to ischemic heart disease, cancer, stroke, etc. were all lowest in people who slept 7 or 8 hours per night. However, people who slept less or too much were at increased risk. Specifically, men who slept 6 hours or less, or 9 hours or more, had a total age-specific mortality rate 1.7 times higher than men who slept 7 or 8 hours per night; for women, this figure was 1.6.
In addition, sleeping too much also impairs cognition and increases the risk of death in adults.

How to overcome oversleeping?
Excessive sleeping, also known as hypersomnia or narcolepsy, affects 2% of the world's population. People with this condition typically need 10-12 hours of sleep each night to feel adequate.
There are many causes of this condition such as frequently waking up at night, disrupting sleep, or life impacts that prevent many people from having adequate rest time. Over time, this creates a feeling of excessive fatigue, and when they have time to rest, they can sleep up to 15 hours at a time.
In addition, the phenomenon of sleeping too much can also be related to sleep apnea, thyroid problems, sleep disorders, stress or heart disease...
Therefore, in cases of excessive sleeping for more than 6 weeks, a specialist should be examined specifically. However, along with the treatment process, you can take some additional measures to ensure normal sleep. Specifically:
Go to bed and wake up at a fixed time. Do not use electronic devices 2-3 hours before going to bed. Keep the bedroom warm, airy, with suitable lighting… Do light exercise before going to bed. Do not use caffeinated drinks before going to bed…
The relationship between sleep duration and mortality, cognitive decline, obesity, metabolic disorders, cardiovascular disease, etc. is U-shaped. The U-shaped phenomenon shows that sleeping too little and sleeping too much (over 9 hours/day) are related to many poor health outcomes and this impact is cumulative./.