The Science of Sleep and Brain Health

A sleep scientist explains the importance of sleep to your brain, shares what the scientific community knows about the connections between sleep apnea and brain health, and offers tips for healthy sleep. Guest: Kate Sprecher, postdoctoral research associate, University of Colorado at Boulder

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doctor kate sprecher
Kate Sprecher, PhD


Nathaniel Chin: Welcome to Dementia Matters, a podcast presented by the Wisconsin Alzheimer's Disease Research Center. Our podcast is here to educate you on the latest research, caregiver strategies, and available resources for fighting back against this disease. I'm your host, Nathaniel Chin. Thanks for joining us.

Dr Kate Sprecher is a postdoctoral researcher associate studying the impact of sleep loss and circadian misalignment on brain performance and on the microbiome. She is passionate about the power of sleep as a pillar of health and has done research in New Zealand, the USA, Nepal, and Canada. Some of her work has focused specifically on the role of sleep and Alzheimer's disease with the goal of improving diagnosis and treatment. Thank you for joining us on Dementia Matters, Dr Sprecher.

Kate Sprecher: Great to be here.

Nathaniel Chin: Now to begin, why sleep?

Kate Sprecher: Well, I can answer that in a couple of ways. First of all, just in general, sleep I just find really fascinating because everybody does it and as soon as you mentioned that you studied sleep, everybody that you meet has questions about it, so it's clearly something that has a massive impact on people's lives and that people are thinking a lot about and they're really aware of when their sleep isn't working for them.

Nathaniel Chin: I bet you're one of the most popular people at a dinner party.

Kate Sprecher: Yeah. I hear a lot about people's sleep problems.

Nathaniel Chin: So when looking at sleep, what are the variables that we do need to consider?

Kate Sprecher: I think most people are aware of duration. So how much sleep you're getting or how long you're sleeping for. The best way that people can figure out how many hours they need is to take a little vacation, sleep, sleep, sleep until you're not tired anymore, and then see how much sleep you need. So basically catch up and then figure out how much you need to just kind of wake up naturally in the morning. One thing that people don't think about as much is also when you're sleeping. So keeping a really consistent sleep schedule is also really important. It helps you sleep better and it also makes you more alert during the day.

Nathaniel Chin: Well, in addition to the timing, are there other things that as a researcher you need to consider?

Kate Sprecher: Yeah. So what I have looked at a lot in the past, is brain activity while you're sleeping, and that's something that people at home are not going to be able to assess for themselves. So we have people come into the lab and we their brain activity while they're sleeping and there are certain brain rhythms that are really important for things like memory and learning. So those are especially relevant to studying dementia.

Nathaniel Chin: When we think about brain activity and rhythms, does that get affected or is that impacted by interruptions in our sleep? Having to get up to go to the restroom or tossing and turning?

Kate Sprecher: It is a little. Yeah. So basically when you're sleeping, you go through several stages of sleep, you get into deeper and deeper sleep and your brain rhythms change as you get into those deeper stages of sleep. And once you wake up you kind of start back where you were and the shallow sleep and you have to get back into that deep sleep. So if you're waking up a lot in the night, it may be harder for you to get into that really deep sleep and get those rhythms that are so important for memory and that kind of thing.

Nathaniel Chin: Okay, and you did a lot of research or are doing research on Alzheimer's disease as well. So what is the relationship between sleep and Alzheimer's disease?

Kate Sprecher: Yeah, so actually a couple of the studies that I did were done at the Wisconsin Alzheimer's Disease Research Center. And for those I was looking at how sleep was related to the amount of different pathologies in the brain in people who don't have Alzheimer's yet, but who were at risk of developing it. And basically what we found was that people who report having less adequate sleep, so they feel like they're just not refreshed in the morning and not getting the sleep they need, those people are also more likely to have things like amyloid and tau in their brains, which are two really important proteins that we think are involved in developing Alzheimer's and dementia later on.

Nathaniel Chin: Wow. You've been able to show an association between the presence of those abnormalities and someone's simply being able to say, I'm not sleeping well for these reasons.

Kate Sprecher: Yeah, that's right. And I think that's really exciting because sleep is one of those things that we actually have a lot of tools for improving and it's something that people undervalue. So here's this whole big opportunity that we can take to improve people's sleep and potentially improve their brain health at the same time.

Nathaniel Chin: Along the lines of sleep and sleep disorders. What do you think of the relationship between obstructive sleep apnea and Alzheimer's disease?

Kate Sprecher: Yeah, it's really interesting. And that is a very common sleep disorder. So I'm sure many of your listeners either habit themselves or know somebody who does. And there have been studies showing that sleep apnea does predict a greater risk of dementia, and the exact mechanisms are not totally understood right now, but there's a few possibilities. One of them is that sleep apnea wakes you up repeatedly during the night, so then you have that problem we talked about earlier where you're not getting into the deep stages of sleep that are so important for memory and learning, but there's also maybe some possibility that it's causing damage because when you have an apnea, you're basically hold your breath for 10 seconds and so your blood oxygen goes down and that causes stress to your neurons and that could produce some damage. So it could be doing multiple things.

Nathaniel Chin: Does that imply that sleep apnea might be affecting just certain parts of the brain or do you think that any sleep disorder could affect really all of the brain?

Kate Sprecher: I think it could affect the whole brain, but I think that the consequences that we see are most obvious from the parts that are doing these really important tasks that we use all day long.

Nathaniel Chin: That makes sense. And you mentioned something about catching up your sleep and there have been some studies recently that said that this idea of sleeping a little bit more on the weekends may actually make sense. Is there a building evidence that we can regain some of the things that we've lost by sleeping in a little bit more?

Kate Sprecher: So I think sleeping in on the weekend is okay, but it's not ideal. Ideally we'd be getting the sleep we need every night. And there are studies showing that sleeping on the weekend does help us catch up a little but it doesn't catch us up all the way and I'm talking about catching up in terms of your cognitive function and your metabolism, your physiology. So sleeping in on the weekends is like. It's better than not sleeping enough, but it's actually not as good as just sleeping the same amount every night. And that's because our body's systems are on this 24 hour cycle and so keeping a really regular schedule in terms of your sleep and wake and even eating really helps keep all of your body systems perfectly in time. So it's kind of like a machine where every piece is moving and operating together in the optimal way and if you move one piece, the others all have a hard time catching up.

Nathaniel Chin: Yeah, that's really great advice and I know it's hard to do, but I think you're absolutely right on that. And I'm wondering back to the earlier question about the Alzheimer's disease and sleep and the stages. And a lot of the reading that I do, they talk about this thing called the glymphatic system, which is simply the removal of that protein, that amyloid protein, during sleep. But it seems to me that a lot of that science has been done in animals and less in humans. Is that the growing evidence though in the, in the human species that it is during sleep, that we clear that protein?

Kate Sprecher: So that still needs to be confirmed in humans and it's very difficult because of the technology that we have, or rather that we don't have. So people have been trying to find ways of confirming that and they haven't published their results yet. So that's something that we're all waiting for with bated breath.

Nathaniel Chin: Okay. So then we'll have to have you come back and talk to us about those results, but in the meantime then, so sleep is clearly important and it's needed. Do you have any specific recommendations for good sleep hygiene?

Kate Sprecher: So I think people have heard a lot of these things like keeping the regular schedule, making sure you have a quiet place to sleep, avoiding using screens in the hour or two before bed. So if you're on your phone, you may have heard of this blue light that comes from a screen and that helps you stay awake, which is not really what you want in the evening. So avoid looking at your phone. If you must, there are filters you can put on that make it kind of more yellow. But then one that people don't seem to think about nearly as much is light. So basically if you can keep your light exposure the same all year, then you will sleep at roughly the same time all year. So in winter that means you might need to have a light that turns on in the morning as if there was an earlier sunrise. In summer, it might mean that you need to draw the shades earlier in the evening so that you can make it darker for yourself, because the timing of your sleep is all about when you last got sunlight on your eyeballs, basically.

Nathaniel Chin: You know, I haven't heard that before and that's great advice. Okay. And you know as a Geriatrician, I'm appreciative that you didn't mention medication because we know that those are not helpful in the long run.

Kate Sprecher: Yeah. Medications are maybe helpful if you have something like jet lag or some sort of temporary issue, but in the long run they just cause more problems than they solve, unfortunately.

Nathaniel Chin: Well, Dr Sprecher, I really want to thank you again for being on dementia matters and we are going to have you in the future when more of these studies come out.

Kate Sprecher: I would love that. And I do want to point out before I go that it might sound scary that if you're not sleeping well, you might get dementia, but the fact is that there are many ways to improve sleep and I really encourage anyone who's having sleep issues to just talk about it with their doctor because there might be more they can do then they realize.

Nathaniel Chin: That's great advice. Thanks again.

Kate Sprecher: Alright, thank you.

Nathaniel Chin: Dementia Matters is brought to you by the Wisconsin Alzheimer's Disease Research Center. The Wisconsin Alzheimer's Disease Research Center combines academic, clinical, and research expertise from the University of Wisconsin School of Medicine and Public Health, and the Geriatric, Research, Education, and Clinical Center of the William S. Middleton Memorial Veterans Hospital in Madison, Wisconsin. It receives funding from private, university, state, and national sources including an NIH/NIA grant for Alzheimer's Disease Centers. This episode was produced by Rebecca Wasieleski and edited by Alex Wehrli. Our music is "Cases to Rest" by Blue Dot Sessions. If you're interested in learning more about the Wisconsin ADRC, check out our website at If you have any questions or comments, don't hesitate to let us know. Thanks for listening.