In this video blog, Dr. David Perlmutter discusses the importance of restorative sleep for brain health and examines new research published in Neurology that links prolonged nightly sleep (>9 hours) to a higher risk of developing dementia and Alzheimer’s disease. The study followed over 2,000 dementia‑free adults (average age ~72) for about ten years, categorizing sleep duration into <6 hours, 6–9 hours (reference), and >9 hours. Results showed that participants who regularly slept more than nine hours had a significantly greater incidence of all‑cause dementia and Alzheimer’s compared with the 6–9‑hour group, with the risk especially pronounced in individuals without a high‑school education, suggesting a role for cognitive reserve. Dr. Perlmutter emphasizes that excessive sleep may not be protective; instead, it could be an early marker of neurodegeneration affecting brain regions that regulate sleep (e.g., the suprachiasmatic nucleus). He also notes other modifiable risk factors—regular exercise, low‑carbohydrate diet, and blood‑sugar control—that can influence dementia risk. The overall message is that there appears to be a “Goldilocks” sweet spot for sleep (approximately 6–9 hours), and that more sleep beyond this range may signal early brain changes rather than confer benefit.
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Hello everyone, I'm Dr. David Perlmutter. We have certainly dedicated a lot of information to the understanding of the importance of sleep. We know that restorative sleep is a really important action for us during the time that our brain is able to basically consolidate thoughts into memories and even go through the process of cleaning itself up. Uh-huh. Helping rid itself of various types of debris and toxins. We know that there is obviously a significant increased risk of various types of issues, medical problems, in individuals who do not receive an adequate amount of restorative sleep. Uh, it's why I've been such a big proponent of people getting a sleep study like I had myself. Talked about that in, uh, the Grain Brain Whole Life Plan. We understand that there is pretty much a sweet spot in terms of what is an ideal amount of sleep to get. And what I think really bears some review is the notion that there may be some associations with too much sleep that might be related to things that are detrimental. In new research that was just published in the journal Neurology, the study I'm referring to is entitled Prolonged Sleep Duration as a marker of early neurodegeneration predicting incident dementia. Researchers looked at a group of over 2,000 individuals aged approximately 72 years. These are individuals without dementia. They followed them for about 10 years and determined who became demented and who did not, and they asked these individuals at the beginning of the study and during the study How much sleep are you getting each night? They divided those— the groups into less than 6 hours being a small amount of sleep, between 6 and 9 hours as the reference group that they would compare the study to, and greater than 9 hours of sleep being a prolonged experience with sleep. And what did they find? Well, let's have a look at some graphs that I've developed from their data. This first graph is a look at all causes of dementia over the 10-year period. The top curve represents those individuals who slept greater than 9 hours as an average each night versus those whose sleep was between 6 and 9 hours on the bottom curve. And I think that you'll see a— as time goes on, that these curves certainly separate, that there's a significant increase correlation of dementia of all types in individuals who sleep 9 hours or greater. In the next graph, a similar type of graph, but this is looking specifically at Alzheimer's patients, and what do we see? Again, those individuals on the top of the graph in the, the red curve are those individuals who are getting 9 hours or more of sleep each night, and again, at greater risk over the 10-year period for the development of Alzheimer's disease in comparison to those sleeping between 6 and 9 hours in the bottom curve. Now, this last graph I think is very interesting, and it looks at the relationship between the duration of sleep and all causes of dementia, but specifically in individuals who did not obtain a high school degree. Now, Why is this important? It's important, first of all, because it really, I think, drives home the point of there being a sweet spot of, you know, sort of the Goldilocks mentality of one bed was too hard, one bed was too soft, but yet one bed was just right. And in this case, we know it— that it looks like, according to the data, that the amount of sleep that seems best is between 6 and 9 hours, that if you routinely are getting more than 9 hours of sleep each night, it is related to increasing dementia and Alzheimer's risk. And importantly, that, that risk is amplified in individuals who do not have perhaps the cognitive reserve of having obtained at least a high school education. The point being that if you obtain that high school education and you're— are involved in learning, And we see data similarly with even higher levels of education, you build up a reserve in terms of brain functionality. Well, you know, we can't rewrite our back— backstories in terms of our history of education, but what we do know is that there are certain things that are related to increased or decreased risk of becoming demented. Certainly physical exercise, low carbohydrate diet, keeping blood sugars low. And it looks like, according to these data, that there's a relationship between higher hours of sleep a night and increasing risk of dementia, and specifically Alzheimer's, once you get to the 9-hour point and above. But the authors really make a very important point, and I think this bears repeating, and that is that it may be that The prolonged sleep may be a marker of early brain degeneration, indicating that there may be degeneration in the parts of the brain that regulate the amount of sleep that we have. Areas of the brain that, for example, interpret light, the suprachiasmatic nucleus if you want to be technical, that appreciate how much light is shining on the retinas And then balance the output from the pineal gland of melatonin so that when people are sleeping more than 9 hours, it might be an early sign of brain degeneration, which is not to say then that the take-home message is to get, you know, 8.5 hours and set an alarm so you can get up because that may somehow be protective. It may work in the other way. But again, I think it's really worth, you know, looking at these data to understand that, you know, while we often say that if some is good, more is better, might not necessarily be the case all around. We know that, for example, having some vitamin D as a supplement is good, but maybe taking too much might not be ideal. That exercise is good, but you can overdo it. And similarly, that maybe getting too much sleep might have a detrimental effect upon the brain, or— Perhaps it is simply an early sign of brain degeneration. So I hope you enjoyed today's video blog, really interesting information, and I think it really tends to add to our knowledge base about what may or may not be good for the brain. Thanks for joining me. I am Dr. David Perlmutter. Bye for now.
