The Damage of Too Little Sleep

21-50 The Damage of Too Little Sleep

Reed Pence: This is Radio Health Journal. I'm Reed Pence. This week: How not getting enough sleep is way worse for the body and mind than we ever suspected.

DeSouza: In fact, you are increasing levels of amyloid—that is a hallmark of Alzheimer's disease—even after one night of sleep deprivation.

Pence: Sleepless nights, dementia, and heart disease when Radio Health Journal returns... Most people stumble out of bed each morning wishing they could hit the Snooze button again. The average American gets 7 hours of sleep each night, and a lot of people get less than six. Some insist they do just fine sleeping so little. And it's true, some people are genetically able to function well on that. But scientists say that accounts for only about 3% of the population. For the rest of us, too little sleep is wreaking havoc on our health.

DeSouza: Both the cardio and metabolic effects of insufficient sleep can be pretty dramatic.

Pence: That's Dr. Chris DeSouza, Professor of Integrative Physiology at the University of Colorado, who studied the effects of lack of sleep on the body.

DeSouza: When people chronically have insufficient sleep. And this is sleep less than 6 hours per night on a habitual basis, and even maybe in a one-time basis, you can have some detrimental effects, both cardiovascularly and metabolically. So it's associated with an increased risk of cardiovascular disease. Our lab and others have shown that insufficient sleep will impair how well blood vessels work. It will impair their ability to vasodilate. The blood vessels will want to vasoconstrict more. It impairs the ability to release important clot-busting agents that help to reduce the risk of heart attack and stroke. From a metabolic standpoint, it increases the risk of being obese. It also increases the risk of diabetes.

Pence: Those risks have been known for a long time, but what's happening now is that scientists are starting to understand some of the mechanisms behind those risks, with the goal of eventually preventing them. For example, a lack of sleep impairs the endothelium—the single-cell thick lining of the blood vessels.

DeSouza: When they become impaired, they don't function properly. And the key functions of these very important cells are to regulate how blood vessels work. So if you need to increase blood flow, they'll stimulate the blood vessels to vasodilate. If you need to reduce blood flow, they'll stimulate the vessels to constrict or reduce in size. And what we found is insufficient sleep impairs that function. So, they're unable to vasodilate properly. And when blood vessels, particularly arteries, are unable to vasodilate properly, this is associated with an increased risk of both a heart attack and stroke.

Pence: DeSouza's study in the journal Experimental Physiology finds that people who don't get enough sleep have only about half the levels of several key microRNAs in the blood. Those are molecules that seem to help clean up what you could call 'garbage proteins' from the bloodstream.

DeSouza: MicroRNAs are small molecules that help to regulate essentially all functions of cells. They're the breaks of cells, if you will, because they help to decrease certain proteins and reduce their functionality. And in the study that you're just talking about, we noted that in individuals who sleep less than 6 hours per night, the levels of key vascular-related microRNAs that are atheroprotective—meaning that they are important for the protection against cardiovascular disease—well, these circulating microRNAs are reduced and there are lower levels of these important microRNAs.

Pence: Now, that doesn't prove that a lack of sleep is what's causing the drop in microRNAs, nor that it's the reason endothelial cells are damaged. But that's the theory: that the body doesn't have enough time to clean up its internal waste when we sleep too little.

DeSouza: That may very well be one of the underlying mechanisms—that we aren't providing enough time for these cells to reset, if you will, or to repair any damage that has happened during the course of a day, or during the course of several weeks. So that's certainly one plausible hypothesis—that the cells do need time to regenerate and to restructure. And when you deprive them of that, then this leads to dysfunctional cells.

Pence: However, it's not always the case that if a little more sleep is good, a lot more sleep is better. DeSouza says they've found some of the same bad effects in people who sleep too much—more than about 9 hours a night. That makes the sweet spot for sleep about 7 to 9 hours per night, every night.

DeSouza: There have been wonderful studies demonstrating that 'makeup sleep' on weekends where somebody will say, 'Well, I didn't sleep as much during the week. I'll just sleep more on the weekends.' Unfortunately, that doesn't work. So the focus has to be on creating a behavioral aspect where the importance of nightly sleep is taken as part of just everyone's general health.

Pence: However, it's not just the quantity of sleep. It's also the quality.

DeSouza: We see the similar types of vascular and metabolic dysfunction, people with apnea, for example, or people who sleep and wake during the night. So it's both quantity and quality of sleep that have these effects. And currently, working with colleagues at the University of Colorado, we are trying to determine whether if you improve people's sleep organically—not aided by any type of Pharmaceuticals—will this help to restore some of the impairments that we're seeing with insufficient sleep?

Pence: And just as it appears, the bloodstream may clear out its trash at night, other parts of the body do as well.

Dr. Ehsan Shokri-Kojori: One of the main ongoing maintenance processes that we've been researching is clearing metabolic waste from the brain. That particularly happens more strongly during sleep.

Pence: That's Dr. Ehsan Shokri-Kojori, a Research Fellow at the National Institutes of Health Laboratory of Neuroimaging.

Shokri-Kojori: There has been this new understanding about the glymphatic system—basically that has been responsible for clearing a lot of metabolic waste from the brain. What happens is basically... on its way, it picks up metabolic waste, such as beta-amyloid—we have been researching lately... And it helps to basically remove that from the space between the cells. And that is important because a lot of these waste products if you don't get it cleared can basically accumulate and lead to certain diseases, such as Alzheimer's. So this clearing generally happens all the time, in body and brain. But it has been shown that sleep actually facilitates that. We have been targeting this beta-amyloid compound that has been implicated in Alzheimer's and how maybe lack of sleep can essentially affect that.

Pence: Shokri-Kojori and his team's study in the Proceedings of the National Academy of Sciences (PNAS) shows that a single night's lost sleep increased beta-amyloid in the brain by about 5%.

Shokri-Kojori: With every night of sleep, we are facilitating or helping to facilitate this clearing process. So it is not that we need to accumulate a lot of sleepless nights to impair the function of the system. So this clearing process is active and we observe it readily as we fall asleep. It essentially kicks in. And if it's not working, for example, because of lack of sleep, we would see the consequences. But to what extent is damaging and to what extent we can tolerate it? I think it's a different question.

Pence: However, the study also shows that not everyone suffers the same accumulation in the brain after the same loss of sleep. Some were much worse than others. But the more accumulation of beta-amyloid, the more tired and unhappy the subjects were.

Shokri-Kojori: It appeared to be, in fact, predicting mood outcome. So we did see individuals basically reporting worse mood outcomes following sea deprivation. And the extent to which they showed worsened mood was, in fact, correlated with how much they showed increases in levels of amyloid-beta in their brain.

Pence: The team also found that beta-amyloid accumulation from sleep loss was not uniform all over the brain. The areas most strongly affected are among those tied to Alzheimer's disease.

Shokri-Kojori: We've been speculating, for example, if lack of sleep can lead to increases in levels of compounds are related to these diseases, they would be in regions that are more prone to those areas. We did see elevation in the thalamus and hippocampus. Not necessarily are all of these regions are among the first that are affected by Alzheimer's disease, but they are among the first.

Pence: So does that mean that getting less than 6 hours of sleep every night increases your risk of Alzheimer's? That's exactly the question choke Shokri-Kojori is trying to answer.

Shokri-Kojori: We are actually really concerned about this issue, and what we are basically trying to research here is whether there is this connection—would lack of sleep be an independent risk factor for developing Alzheimer's disease? And what we are seeing, for example, in our work is basically suggesting that, in fact, you are increasing levels of beta-amyloid—that is a hallmark of Alzheimer's disease—even after one night of sleep deprivation.

Pence: So would a good night's sleep reverse the damage? Scientists don't know.

Shokri-Kojori: It well may be that this is going to happen, but it could be also the case that if you have really poor sleep for an extended amount of time, then catching up or basically trying to sleep adequately in the following nights may not be as effective.

Pence: It's already well known that people with Alzheimer's disease don't sleep well. So it could be that a lack of sleep eventually sets up a vicious cycle of poor sleep creating more plaques in the brain, leading to even more sleep loss, and more plaques. And a new study in the Journal of Neuroscience adds to the evidence of that. It finds that people who don't sleep well in their 50s have more protein tangles in the brain, an Alzheimer's risk factor. But it's even more basic than that. It's pretty clear from all this new research that poor sleep can lead to a whole variety of bad health outcomes. So we can't treat sleep as the disposable part of our day.

Shokri-Kojori: You're certainly affecting levels of compounds that are implicated in neurodegenerative disorders, with even lack of one night of sleep. There's also an abundance of evidence that poor sleep can affect the body too. You can, in a way, affect your metabolism. It could lead to weight gain. It could affect your cardiovascular health. So it is important that, basically, sleep is for us an important part of our life cycle, and we really need to take care of it as we do when we are awake. We do, for example, exercise. Maybe we watch our diet, but steep is definitely, I think, another item on the to-do list to watch and be careful about. And we probably should do a lot more research also on how to make sure individuals get good enough, but also good quality sleep.

Pence: You can find out more about all of our guests on our website, radiohealthjournal.org. An archive of our segments is also there, as well as on Apple Podcasts, Google Play, and Spotify. I'm Reed Pence.