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Neuro Athletes,

There is a difference in sleep stages and there is equally a difference in the quality of each stage. It’s incredibly important that we are able to differentiate between the different stages so we know what we are optimising and why. I recently wrote a part I to this article and it was very well received so I wanted to put the part II out this week.

Most of you wear some kind of wearable. However, many of you only look at the data without really understanding how to optimize the data.

Despite a better understanding of the genetic, physiological and environmental factors involved in the sleep-wake regulation, many people still don’t get enough sleep—in fact, as many as one-third are not sleep enough, according to the National Sleep Foundation. One potential reason is the public’s lack of information or even misinformation about sleep. In other words, a lot of people still believe a lot of the common myths when it comes to getting a good nights sleep. These myths aren’t supported by current scientific evidence and are likely subtracting from your sleep health. 

When thinking about getting the sleep you need, it’s normal to focus on how many hours of sleep you get. While sleep duration is undoubtedly important, it’s not the only part of the equation.

It’s also critical to think about sleep quality and whether the time spent sleeping is actually restorative. Progressing smoothly multiple times through the sleep cycle, composed of four separate sleep stages, is a vital part of getting truly high-quality rest.

Each sleep stage plays a part in allowing your mind and body to wake up refreshed. Understanding the sleep cycle also helps explain how certain sleep disorders, including insomnia and obstructive sleep apnea can impact your sleep and health.

Understanding SWS Sleep

A typical good night’s sleep follows a sequence of non-rapid-eye-movement (NREM) sleep which comprises three stages (N1, N2, and N3), and rapid-eye-movement (REM) sleep. 

Stage N3 or deep slow-wave sleep (SWS) optimizes memory consolidation and brain wastes clearance. Generally, as the sleep progresses through the NREM sleep, one can observe a continuous slowing of the brain activity in the electroencephalogram (EEG). The deep NREM sleep stage, in particular, is associated with the slowest brain waves during sleep.

Through a Polysomnography (PSG) or sleep study, slow-wave sleep is characterized by:

1. Slow or absent eye movement. As opposed to REM sleep, people who are in slow-wave sleep exhibit little to no eye movements. Hence, it is categorized as NREM sleep.

1. Moderate muscle tone. The muscle tone is significantly reduced in SWS sleep. However, unlike REM, the body is not paralyzed.

1. EEG synchronization. This period of sleep is known as slow-wave sleep because the brain waves are synchronized. It produces delta waves, which are slow waves with a large amplitude and low frequency that range from 0.5-4 Hz. 

The two main hormonal processes that happening during deep sleep

Although the brain and the body are most inactive during this sleep stage, the internal body environment is maintained to keep the body functioning through the regulation of hormone secretion. Two hormones were found to be strongly or particularly associated with SWS: 

Growth hormone (GH), a hormone that promotes cell and tissue growth in the body. Its secretion is specific to SWS and is strongly correlated with the power of EEG delta activity. In other words, the higher the EEG delta activity, the higher the rate of GH secretion. GH also increases glucose production by the liver and kidney to maintain glucose supply for the brain and other tissues such as red blood cells while the body is in the fasting state. 

Thyroid-stimulating hormone (TSH), a hormone that controls the production of thyroid hormones is suppressed during SWS. As TSH is associated with increased insulin resistance, the suppression of TSH during SWS may be a protective mechanism against metabolic diseases like diabetes.

Deep Sleep Blockers

While sleep can be affected by various factors, some of them were found to specifically inhibit SWS. For example, 

1. Caffeine, which keeps us awake, does it at the cost of SWS. Caffeine prevents the interaction between the brain receptors and adenosine, a peptide that builds up during wakefulness and makes us feel sleepy. This reduces the sleep drive and hence, reduces SWS. Previous studies have shown that 100 to 400 mg of caffeine (equivalent to one to four 8-ounce cups of coffee) intake during or 6 hours before bedtime increases sleep latency and decreases EEG delta activity.

2. Medications such as psychoactive drugs (e.g., benzodiazepine and opioid) are seen to reduce SWS in healthy adults who took the drugs. Benzodiazepines, for example, binds to the GABAA receptors in the area of the brain called the cortex, which is crucial for memory consolidation, and inactivates the neurons. This leads to the inhibition of neurotransmission and subsequently, disrupts the synchronization of the brain activity, as reflected in the absence of EEG delta activity. 

3. Excessive daytime naps can reduce SWS. Generally, SWS is regulated by homeostatic regulation. This means that when a person stays awake, their sleep pressure will continue to build up. The amount of sleep pressure will then affect the depth and duration of a person’s sleep. Daytime naps were shown to decrease the sleep pressure and subsequently, reduces SWS during the night. This may lead to future health complications as short nocturnal sleep appears to be associated with diseases like cognitive disorders and mortality.

Premium Members:

1. The report for our premium members will be delivered at at 11:17am ET on Tuesday the 19th of October. The report will cover wearables and how to read the data, make sense of every piece of metric that is given with the Oura ring and WHOOP and how to optimise the data.

2. A video will accompany the report followed by a Q&A for the members to ask questions!

If you are a coach, athlete or high performer waning to gain an in-depth understanding of how to optimise data for performance, please consider becoming a member.

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