Bill Clinton.

 

Barack Obama.

 

Donald Trump.

 

What do these three have in common? It’s not what you think! These three, along with other notables such as Nikolai Tesla, Thomas Edison, and Benjamin Franklin, all have boasted they can get by with less than five hours of sleep at night. But that’s not an asset . . . it’s a LIABILITY.

What is so wrong about sleeping less?

 

Plenty.

 

Numerous studies have shown that sleep deprivation increases your risk of obesity, diabetes, and cardiovascular disease. It hinders your immune system.

 

We have all experienced decreased cognitive performance after a poor night of sleep, but the problem goes deeper than this. Chronic sleep deprivation has been linked to accelerated brain aging and an increased risk of dementia.¹

 

Pillow Talk: The Stages of Sleep

Sleep is a complex process, occurring in separate stages - each of which plays a critical role in our overall health. The importance of quality rest, especially during deep sleep, must be understood.

 

Generally, a typical night of sleep has 4 - 5 sleep cycles, each lasting 90 - 120 minutes. Each cycle contains two phases of sleep: non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. The NREM phase begins first and consists of 4 stages that we can simplify into either light sleep and deep sleep.

Light sleep begins first and shows the typical signs we think of as sleep: a drop in body temperature, slower heart rate, and slower brain waves.

 

It is the following two stages that we will focus on:

 

Deep NREM sleep (or slow-wave sleep) is the deepest and most restorative phase of the sleep cycle. During which, delta waves – slow, high-amplitude brain waves can be seen on EEG. This is the crucial phase where certain processes occur:

 

• Tissue repair
• Muscle and bone-building
• Strengthening of the immune system
• Memory consolidation

 

REM Sleep is the final stage during which dreaming occurs most often. Your brain is active while your body remains immobile, aiding cognitive functions such as learning and memory.

 

The amygdala, an almond-shaped area in the brain, is one of the key players during REM sleep. Along with the hippocampus and prefrontal cortex, it processes memory and emotions, especially those related to fear.

 

REM sleep is essential for the regulation of the amygdala; disrupted or insufficient REM can lead to emotional distress, including anxiety and depression - both of which can potentiate dementia.²

Gasping for Sanity: Sleep Apnea’s Role in Mental Decline

 

Sleep apnea is a problem for many, but what many do not understand is the role it plays in increasing your risk for dementia, including Alzheimer’s disease. Sleep apnea exerts itself in several areas:

 

Oxygen deprivation (hypoxia) – A study at the University of Queensland showed that sleep-deprived mice had neurons that mimicked those of patients with Alzheimer’s disease.³

 

Disrupted NREM and REM sleep – As mentioned above, disrupting these increases your risk for dementia.

 

Inflammation – Repeated sleep disruption and hypoxia increase inflammation throughout the body, including the brain.

 

In 2022, a meta-analysis found that individuals with sleep apnea had a 43% higher risk of developing any type of cognitive disorder, which included a 28% increased risk of developing Alzheimer’s disease.⁴

 

On a more positive note, treating sleep apnea with continuous positive airway pressure (CPAP) may help reduce this risk.³

Your Brain’s Janitor Only Works Nights

Your body clears waste from its cells through the lymphatic system. This process supports critical functions and removes excess fluid and metabolic waste.

In recent years, a similar system was discovered in the brain. Like the lymphatic system for the rest of the body,

the glymphatic system plays a crucial role in maintaining your brain health.

 

Of note, the glymphatic system works primarily during sleep, particularly during deep NREM sleep .

In this process, cerebrospinal fluid (CSF) enters the brain along the outside of arteries, flows through the brain tissue, and exits along veins, carrying out waste products.

 

It is helpful to think of your glymphatic system as your brain’s janitor. When the lights are out, it goes to work, cleaning the crevices and removing the trash.

 

But the glymphatic system does more than remove waste. It also helps distribute glucose, lipids, amino acids, and neurotransmitters throughout the brain.

 

 

Glymphatic failure . . .a final common pathway to dementia

 

When Your Janitor Goes On Strike

 

When the waste system in your house stops working, things go bad in a hurry. The same principle applies to your brain’s waste system, although the changes occur over time.

 

Dysfunction in your glymphatic system has been implicated in several neurological disorders, such as:

 

• Alzheimer’s disease - decreased glymphatic function can lead to the accumulation of beta-amyloid plaques, a hallmark of the disease.
• Traumatic brain injury - decreased glymphatic clearance can hinder the recovery process for traumatic brain injury and stroke.

 

The discovery of the glymphatic system and its pathology has promoted the importance of good sleep hygiene. The gravity of this was demonstrated in Science, which titled their article:  “Glymphatic failure as a final common pathway to dementia.”⁵

 

Further research into the astrocyte water channels and even sleep positions hopes to demonstrate possible treatments for these neurodegenerative disorders.

 

Your Brain’s Night Shift: Why You Need NREM Sleep

We have already stated that deep sleep is essential for brain health in terms of restorative sleep and removing waste products from the brain. Many studies have been done, and more are ongoing, but these are some of the results:

• In a 2023 study published in JAMA Neurology, initial findings showed that a decrease in slow-wave sleep was linked with a 27% increase risk of developing dementia and a 32% increase risk of developing Alzheimer’s disease.
• A senior author of the study above, Matthew Pase, said, “We found that aging was associated with a decline in the amount of the deepest stages of sleep, known as slow wave sleep.”¹
• Decreased quality of slow-wave sleep is associated with increased levels of beta-amyloid and tau proteins - which are present in Alzheimer’s.⁵
• Sleep apnea, as well as other sleep disorders, disrupt NREM sleep and are seen with an increase in cognitive decline and increased dementia.

 

 

Of equal importance is a study from the University of California Berkeley, published in May 2023, which showed that deep sleep may provide a buffer against memory loss for older adults with Alzheimer’s disease. Deep sleep might act as a “cognitive reserve factor” in those with beta-amyloid proteins already present. Matthew Walker, senior author of the study, was encouraged by the findings because, as he said, “. . . sleep is something we can change. It is a modifiable factor.”⁶

Sleep Like Your Brain Depends On It (Because It Does)

We all understand that sleep is important for our overall well-being, but it is even more critical for our brain health to reduce our dementia risk as we age. Many of the following suggestions are known, but there are a few new ones. It is still worthwhile to attempt to implement at least some of these. After all, your brain is depending on you!

 

1. Consistent sleep schedule: Going to bed and waking up at the same helps maintain your circadian rhythm.
2. Relaxing bedtime routine: Meditation, yoga, or gentle stretching before bed can help you decompress your brain. Journaling can also help you decompress by jotting down any last concerns or “to-dos” for the upcoming day or listing a few things you are grateful for.
3. Optimized sleep environment: Dark, quiet, and cool bedroom. Our ancestors likely slept with cooler temperatures as the sun set and nighttime temperatures dropped.

Natural cooling aligns with our circadian rhythms, which promotes sleep. As mentioned earlier, our body temperatures naturally drop during deep sleep. Dr. Matthew Walker recommends a bedroom temperature of 65-68 degrees Fahrenheit.

1. Limited blue light exposure: Ideally, limit screen time at least one hour before bed. This includes TVs, tablets, laptops, and smartphone screens. Many personal devices now have a “sunset” feature that removes the blue light from the screen. Take advantage of this by enabling it to start every day around 2-3 hours before your ideal bedtime.
2. Exercise regularly: Aim for 30 minutes of moderate exercise most days of the week. Be careful not to exercise too close to bedtime. Increases in cortisol and core body temperature during exercise can promote wakefulness, so try to fit your workouts in ideally before dinnertime or at least 2-3 hours before bed.
3. Diet: Avoid large meals, caffeine, and alcohol close to bedtime. Some studies support intermittent fasting for improving glymphatic function.⁵ When your body is digesting food, your metabolism works, increasing your body temperature. Blood flow is also redirected to your GI system, which leaves less for your brain.

 

“But a drink helps me relax at night.”  Having one drink at dinner likely won’t have much of an effect on one’s sleep quality. However, two or more drinks close to bedtime will not only increase your chances of having to wake up and urinate, but the effects of alcohol on the brain decrease the quality of REM and NREM stages your brain needs to recover during the night.

 

Instead, your body will alternate between light, non-restful sleep, and semi-awake states. This fragmented sleep has been shown to increase cognitive impairment and Alzheimer’s disease risk.^7,8

1. Manage stress: Practice relaxation techniques for relaxing bedtime routines above.
2. Sleep position: Side position may enhance glymphatic function versus back or stomach.⁵
3. Treat sleep disorders: Consult your healthcare provider if you suspect you have sleep apnea.

Sleep: Your Best Investment for a Better Tomorrow

Sleep is not a luxury but a necessity for every aspect of our lives. The relationship between sleep and your brain health has been established, extending beyond mere rest. But it isn’t just your brain that benefits from sleep - cardiovascular disease, obesity, and diabetes can all be reduced by getting consistent quality sleep. Thomas Dekker said, “Sleep is the golden chain that ties health and our bodies together.” Prioritize your sleep now, and just might save your brain later.

 

Bibliography

1. Jayandra J. Himali, P. (2023) Association between slow-wave sleep loss and incident dementia, JAMA Neurology. Available at: https://jamanetwork.com/journals/jamaneurology/article-abstract/2810957?utm_campaign=articlePDF&utm_medium=articlePDFlink&utm_source=articlePDF&utm_content=jamaneurol.2023.3889 (Accessed: 04 September 2024).
2. Sanford, L.D., Adkins, A.M. and Wellman, L.L. (2022) ‘The amygdala as a mediator of sleep and emotion in normal and disordered states,’ Journal of Integrative Neuroscience, 21(6), p. 163. doi:10.31083/j.jin2106163.
3. UQ study explains link between sleep apnoea and dementia (2022) UQ News. Available at: https://www.uq.edu.au/news/article/2022/11/uq-study-explains-link-between-sleep-apnoea-and-dementia (Accessed: 04 September 2024).
4. Guay‐Gagnon, M. et al. (2022) ‘Sleep apnea and the risk of dementia: A systematic review and meta‐analysis,’ Journal of Sleep Research, 31(5). doi:10.1111/jsr.13589.
5. Nedergaard, M. and Goldman, S.A. (2020) ‘Glymphatic failure as a final common pathway to dementia,’ Science, 370(6512), pp. 50–56. doi:10.1126/science.abb8739.
6. Pohl, J. (2023) Deep sleep may mitigate Alzheimer’s memory loss, Berkeley Research shows, Berkeley News. Available at: https://news.berkeley.edu/2023/05/03/deep-sleep-may-mitigate-alzheimers-memory-loss-berkeley-research-shows/ (Accessed: 04 September 2024).
7. Lim, A.S. et al. (2013) ‘Sleep fragmentation and the risk of incident Alzheimer’s disease and cognitive decline in older persons’, Sleep, 36(7), pp. 1027–1032. doi:10.5665/sleep.2802.
8. Minakawa, E.N. et al. (2017) ‘Chronic sleep fragmentation exacerbates amyloid β deposition in Alzheimer’s disease model mice’, Neuroscience Letters, 653, pp. 362–369. doi:10.1016/j.neulet.2017.05.054.