Introduction
What are your brain health and sleep needs? There is a lot of confusion about how much sleep is enough and what impact sleep has on the brain and thinking skills. I hope to answer some of these questions today and help provide some sleep tips. So, let’s dive into it.
Are You Sleeping Enough?
About 40% of adults report that they don’t get enough sleep. Although, this is probably an underestimate since most people are notoriously inaccurate at reporting how well rested they are. People often report being well rested when their performance on tests would suggest otherwise. In fact, the inaccuracy of perception of sleep may actually be related to poor sleep. Did you know that if you are not getting the quantity or quality of sleep you need, you may be at a higher risk of developing problems with your brain health including memory problems or Alzheimer’s Disease?
Sleep Stages
You are probable familiar with the sleep stages to some extent. Let’s talk about them briefly. First there is stage 1 non-REM sleep. This is the initial stage of sleep lasting minutes where people are in a very light sleep and can be easily woken. It is characterized by slow brain waves.
Stage 2 non-REM sleep also lasts only minutes and shows an increase in brain wave frequencies called spindles. Next, we have stage 3 non-REM sleep (deep sleep). This stage is associated with restorative sleep and contributes to feeling of being refreshed. It is also associated with enhanced immune functioning and bodily tissue repair and growth.
Last, we have rapid eye movement (REM) sleep. This stage usually occurs about 5-6 times during the night. This is the stage where dreaming occurs. The amount of time spent in REM sleep decreases as we age.
Sleep and Cognitive Skills
There is good support that stage 3 sleep helps with selecting and consolidating certain types of memories (such as memory for facts). The role of REM sleep and memory is a little less clear. However, there has been support in research for REM sleep in processing procedural memories (memories for how to perform actions). REM may also be important for consolidating emotional memories.
There is also research suggesting that stage 3 and REM sleep may work together to select, reactivate, and store memories. One study also found a 68% increased risk of mild to severe cognitive problems in people who slept poorly. While we still don’t have all the answers as to the role of sleep in memory, we do know that good sleep is vital to our memory function and reducing risk of Alzheimer’s Disease.
So why does sleep impact memory and increase risk of Alzheimer’s Disease? Part of the explanation has to do with a neuronal waste product in the brain called beta-amyloid. While some of this is normal in the brain, excessive build up of beta-amyloid occurs in Alzheimer’s disease pathology. Research has found that sleep helps to clear this out of the brain, helping to rid the brain of this potentially toxic by-product.
Does the Amount of Sleep Matter for Brain Health?
Some studies have found that shorter and longer than average sleep durations are especially linked to cognitive impairment. A metanalysis (study of studies) found those who slept less than 5 hours were nearly 1.5 times more likely to have poorer memory, working memory, and executive functions. Those who slept more than nine hours per night were 1.58 times more likely to have the same problems.
In a large study of older adults, those that slept 10 hours or more had poorer performance on tasks of memory, rapid verbal expression, processing speed, and working memory. There has also been a link between sleep duration, sleep fragmentation, and sleep-disordered breathing and later dementia.
One study estimated that individuals with sleep problems have a nearly 1.7 times higher risk of Alzheimer’s Disease and about 15% of cases of Alzheimer’s Disease may be related to sleep problems. So, what is the sweet spot for the amount of sleep? Overall, 7-8 hours seems to be best for most people.
Sleep Protocols for Better Sleep and Brain Health
- Keep your bedroom cool- The body likes cooler temperatures to sleep.
- Keep a Sleep routine– Routine helps your body and brain prepare for sleep/wake cycles.
- Take a warm shower or bath before bed- The drop in body temperature once you step out may cue your body to prepare for sleep.
- Use your bed for sleeping and sex only- As soon as you wake up, get out of bed and don’t return to it until you want to go to sleep for the night.
- Avoid alcohol- Even though alcohol helps you get to sleep faster, it disrupts quality of sleep including decreasing the amount of time spent in REM sleep,
- Avoid nighttime blue light exposure- Try blue light-blocking glasses, make sure bulbs in home at night are warm in color temperature.
- Keep your smartphone away from your bed- Keep it out of arm’s reach to limit the temptation.
- Keep your room dark- Even a little bit of light can disrupt sleep. Try blackout curtains or a sleep mask.
- Limit Caffeine- Limit caffeine consumption to 4 p.m. at the latest, maybe even earlier if you are a genetically slow metabolizer.
- Stop eating at least an hour before bed- Nighttime eating can disrupt sleep.
- Get direct sunlight within 20 minutes of waking, especially during daylight saving time or when traveling- Bright light helps anchor the body’s circadian rhythm, which regulates the natural ebb and flow of your sleep-wake cycles.
References
- Ackermann, S., & Rasch, B. (2014). “Differential effects of non-REM and REM sleep on memory consolidation?” Current Neurology and Neurocience Reports 14(2): 430.
- Bubu, O.M., Brannick, M., Mortimer, J., et al. (2017). “Sleep, cognitive impairment, and Alzheimer’s disease: A systematic review and meta-analysis.” Sleep 40(1) 1-18.
- Lo, J. C. et al., (2016). “Self-reported sleep duration and cognitive performance in older adults: A systematic review and meta-analysis.” Sleep Medicine 17:87-98.
- Low, D.V., Wu, M.N., & Spira, A.P. (2019). “Sleep duration and cognition in a nationally representative sample of U.S. older adults.” American Journal of Geriatric Psychiatry (19) 30426-9.
- L. Xie et al. (2013). “Sleep drives metabolite clearance from adult brain”. Science (342) 373-77.
- Peter-Derex, L. (2019). “Sleep and memory consolidation.” Neurophysiologie clinique 49)3): 197-98.
- Sara, S.J. (2017). “Sleep to remember.” Journal of Neuroscience 37(3): 457-63
- Yaffe, K., Falvey, C.M., & Hoang, T. (2014). “Connections between sleep and cognition in older adults.” Lancet Neurology 13: 1017-28.
