Research Wrap: Brain Health and Sleep

Let’s talk about brain health: Sleep

As #DAI progresses with its series of monthly research blogs, we thank Laura Garcia Diaz for our April research blog, focused on the impact of sleep on dementia.

Thank you Laura.

“I live in Canada and on March 13th our clocks went forward one hour. Even though an hour difference may not sound like a lot, the week after the time changes (especially when we lose an hour in the process), I always feel off. Since the topic of sleep has been on my mind lately, I decided to dedicate this blog to it. What does the science tell us about sleep and brain health?

Sleep is essential for life, so it may not be surprising to learn that sleep plays a very important role in keeping our brain healthy. Sleep has been shown to play an important role in helping us remember things, known and memory consolidation, and learning (Krause et al., 2017).

It appears that while we sleep our brain is working hard to help us remember everything we did and/or learned that day. Studies have also shown that abnormal sleep-wake patterns and breathing difficulties while sleeping (for example, sleep apnea) are associated with an increased risk of dementia (e.g., Yaffe et al., 2014).

Although the relationship between sleep and dementia is still being studied, sleep is now recognized as a risk factor for cognitive decline and Alzheimer’s disease. Based on this information, it appears that sleep plays an important role in maintaining brain health as we age.

Although the role of sleep on supporting our brain health has been of interest to scientists for many years, the amount of sleep required for optimal brain health is still unclear (Tai et al., 2022). When reviewing the literature, something that I found interesting, is that going to bed late at night and wake up late in the day has been found to be associated with cardiovascular disease and mortality (Knutson et al., 2018; Partonen, 2015). I have always been told to aim for 7-8 hours of sleep each night.

When reviewing the literature, I found that both short (less than 7 hours) and long (more than 10 hours) sleep duration appears to impact cognitive performance (for example, attention and working memory) (Hirshkowitz et al, 2015; Gildner et al., 2014).

However, some studies have also shown no relationship between sleep duration and cognition (e.g., Saint Martin et al., 2012). Interestingly, in a recent study, six or less hours of sleep at night were found to be associated with a higher dementia risk, when compared to sleeping seven hours (Sabia et al., 2021). Similarly, in another recent study, it was found that peak cognitive performance was associated with seven hours of sleep at night (Tai et al., 2022).

Although the science does not appear to have a definitive answer regarding the sleep required for optimal brain health (particularly for supporting cognition), it does appear that there are benefits to getting 7 hours of sleep at night. I did not conduct a thorough research on this topic, so if anyone is interested in learning more about this, please let me know in the comments and I can dedicate another blog to this.

I thought I’d be good to end this blog with some information about sleep hygiene.

Here are some tips for better sleep:

  • Try to go to sleep and wake up at the same time every day.
  • To prevent you from having to go to the bathroom in the middle of the night, try not to drink a lot of liquids before going to bed.
  • If possible, avoid heavy meals too close to bedtime.
  • Try to relax before bed. Something that I like to do is light yoga followed by a 10 min meditation. It always helps me have a better sleep.
  • If you are a coffee or tea drinker, try limiting your caffeine intake in the afternoon and evening.
  • Technology seems to be everywhere these days, and if you are like me, I often have my phone with me everywhere I go. For a better sleep, try turning off all your devices at least 3—45 minutes before you go to bed.
  • Try to move your body every day!
  • If you are a napper like me, try to restrict your naps to a maximum of 45 minutes.

I have not always prioritized my sleep, but since starting my PhD program I have made an effort to develop good sleeping habits. I am now very strict about my nighttime routine and incorporating the strategies mentioned in this blog has really made a difference!

Do you have a nighttime routine? I’d love to learn what helps you get a good night’s sleep!

Laura

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References

Gildner TE, Liebert MA, Kowal P, et al. (2014). Associations between sleep duration, sleep quality, and cognitive test performance among older adults from six middle income countries: results from the Study on Global Ageing and Adult Health (SAGE). J Clin Sleep Med, 10, 613–621.

Hirshkowitz M, Whiton K, Albert SM, et al. (2015). National Sleep Foundation’s sleep time duration recommendations: methodology and results summary. Sleep Health, 21, 40–43.

Knutson, KL, et al. (2018). Associations between chronotype, morbidity and mortality in the UK Biobank cohort. Chronobiol Int, 35(8), 1045–1053.

Sabia, S. et al. (2021) Association of sleep duration in middle and old age with incidence of dementia. Nat. Commun., 12, 1–10.

Saint Martin, M. et al. (2012). Does subjective sleep affect cognitive function in healthy elderly subjects? The Proof cohort. Sleep. Med, 13, 1146–1152.

Partonen, T. (2015). Chronotype and health outcomes. Curr Sleep Med Rep, 1(4), 205–211.

Yaffe, K., Nettiksimmons, J., & Byers, A. (2014). Sleep disturbances and risk of dementia among older veterans. Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, 10, DOI:10.1016/j.jalz.2014.05.969

Tai, X., Chen, C., Manoar, S., & Husain, M. (2022). Impact of sleep duration on executive function and brain structure. Communications Biology, 5. https://doi.org/10.1038/s42003-022-03123-3