Don’t sleep to much, it’s bad for your brain, science says

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One common knowledge that most people are aware of is the fact that we need an eight hours of sleep everyday to maintain our health. However, regardless of this information, many are still quite unsatisfied when they only have eight hours of sleep especially whenever they’ve gone on a long tiring day. As an end result, they tend to sleep longer than the average sleeping time suggested by the experts.

Well, for some, this is not that alarming because what they only know are the negative health effects of having lack of sleep. However, little did they know, too much sleep could also badly impact one's physical health, especially the brain. 

It is surprising, right? You may be probably doubting this information right now. You may be asking why and how too much sleep can affect your brain. That is why to answer you, listed below are the things that oversleeping can do to you.


It can double your risk of having Alzheimer’s and other forms of dementia

Many are confused with the difference of dementia and Alzheimer’s disease. That is why, before jumping off to the topic, we would like to inform everyone that according to experts, dementia is the term for the group of brain disorders that impair the memory, thinking and behavior of an individual and Alzheimer’s disease is one of the forms or types of dementia. 

Now, heading to the link between oversleeping and Alzheimer’s and other forms of dementia, studies claim that prolonged sleep is not only an indication of this type of disorder but also an early marker of those who are highly at risk to it. 

In a study from the US in 2017, researchers found out that people who regularly sleep more than nine hours every night are twice at risk for Alzheimer’s and other types of dementia. Other studies share the same findings, however they clarify that they are not indicating that oversleeping is the sole cause of dementia. According to them, their studies only suggest that a person who sleeps too much may actually have Alzheimer's disease or other forms of dementia because oversleeping is one of the symptoms of the said disorder.

It can cause you trouble in memorizing

According to a study from Harvard University, too much sleep can affect the memory and thinking of an  individual. After conducting some tests to examine the memory of the participants, the researchers found out that under-sleepers and over-sleepers have poorer performance compared to those average-sleepers.They also added that people who sleep longer than nine or 10 hours can be mentally two years older than those who acquire an adequate sleep of seven to eight hours.

With that said, they recommend that people must really have to have adequate and quality sleep so that their memory will be maintained in later life.

It can intensify your depression

If you are at risk or suffering from depression, it is not good for you to have too much sleep. This is because studies say that oversleeping, just like inadequate sleep, can worsen depression. As a matter of fact, one study of Watson et al., in 2014, claimed that less and too much sleep can not only intensify depression but also increases the chances of acquiring it. Additionally, an article entitled "Physical side effects of oversleeping," (2008), suggests that oversleeping worsen depression because it hinders the recovery process on an individual suffering from it.

It decreases your cognitive ability

Cognitive ability refers to the ability of an individual to think, reason out, plan, brainstorm, and learn from something no matter how complex it is. Surprisingly, this ability can be massively impacted by the duration of sleep. Most of the studies held before suggest that lack of sleep can impair cognitive ability but as time goes by, there are also researches arising and proving that even oversleeping can negatively affect the aforementioned ability too.

To cite one, in 2017 there was an online sleep study launched and considered as the largest sleep study in the world. It has more than 40,000 participants all around the globe with different ages, profession, gender, and lifestyle.

In 2018, the study released a preliminary finding after the researchers conducted several tests to examine the cognitive ability of 10,000 participants.  They then found out that people, regardless of their age,  who regularly sleep more than or less than seven to eight hours every night have lower cognitive performance compared to those who get exactly seven or eight hours of sleep. Reasoning, verbal ability, and identification of complex patterns are some of the cognitive functions affected. On the other note, short-term memory appears to be not influenced with the duration of sleep unlike what previous studies suggest.


LeWine, H. (2020, June 17). Too little sleep, and too much, affect memory. Harvard Health Blog.

Physical side effects of oversleeping. (2008, July 24). WebMD.

Watson, N., Harden, K., Buchwald, D., Vitiello, M., Pack, A., Stratchan, E., & Goldberg, J. (2014, February). Sleep duration and depressive symptoms: A gene-environment interaction. PubMed Central (PMC).

Westwood, J., Beiser, A., Jain, N., Himali, J., Decarli, C., Auerbach, S., Pase, M., & Seshadri, S. (2017, March 21). Prolonged sleep duration as a marker of early neurodegeneration predicting incident dementia. Neurology.

Wild, C., Nichols, E., Battista, M., Stojanoski, B., & Owen, A. (2018, September 13). Dissociable effects of self-reported daily sleep duration on high-level cognitive abilities. OUP Academic.

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