Part 1: Why Sleep?

When we take the first tentative steps on our health and wellness journey, we have certain expectations. We can grasp the importance of regular exercise and sound nutrition, and we recognise that to make progress, we’ll need to make changes in these areas. Many of us are surprised to learn that we are neglecting an – equally important – tenet of health, sleep!

Given that we’ll spend over thirty percent of our lives asleep, we pay little attention to what happens when our eyes close for the night. More than twenty large-scale epidemiological studies – tracking millions of people over decades – have reached the same conclusion; the less we sleep, the shorter our lives. The diseases plaguing developed nations – including heart disease, obesity, and cancer – have all been linked to lack of sleep.

Why Sleep?

The benefits of a healthy sleeping schedule are vast. Sleep has been well established as a crucial memory aid - lack of sleep has even been recognised as a key lifestyle factor in the development of Alzheimer’s disease. It plays a vital role in allowing the brain to make new memories, learn new skills, as well as effectively storing them, while preventing us from forgetting them as time passes.

Increases in speed and accuracy performing automated tasks – such as driving - were directly linked to the amount of deep sleep we get, especially in the last two hours of an eight-hour night of sleep.

For those of us chasing performance – or longevity - sleep accelerates physical recovery from common inflammation, stimulates muscle repair, and helps restock cellular energy in the form of glucose and glycogen.

In short, sleep is essential, and has rightfully earned its place alongside exercise and nutrition in the trifecta of optimal health.

The Two Types of Sleep

There are two types of sleep; NREM (non-rapid eye movement) and REM (rapid eye movement), which both serve distinct functions.

NREM is the first stage of sleep we enter when drifting off and has four phases, each representing a spectrum of depth. In this stage, our brain slows down and enters a reflective mode. This is where we store and solidify new learnings and skills we experience when awake.

After completing the four phases of NREM sleep, we enter a second stage, this time of REM sleep. This is a lighter type of sleep, where brain activity increases significantly. In this stage, our brain is integrating new learnings with existing memories and past experiences, creating innovative insights, and improving problem-solving abilities. It is in this state of REM sleep that we experience our most intense dreams, which is unsurprising when we consider that REM sleep is responsible for fuelling creativity.

In this sense, not all sleep is created equal. The phases we experience late in the sleep cycle are the most important for our health, recovery, and mental acuity. To reach phase four of NREM - and then REM – sleep, we must first navigate phases one through three of NREM sleep. This means that when we sleep less than the eight recommended hours per night, we lose out on valuable phases of the sleep process. If we sleep for six hours, the entire cycle doesn’t condense to accommodate our lessened slumber schedule. Instead, we simply don’t spend much – if any – time in the later phases of sleep, with dire consequences. 

The Effects of Sleep Deprivation

The effects of sleep deprivation are profound; even the smallest restriction can wreak havoc on our concentration. In almost all cases, we need more than seven hours of good quality sleep to maintain our cognitive performance.

While acute deprivation is obviously damaging – think of a big night out on the town, or the “all-nighters” we attempt prior to an exam – the problem runs deeper. Sleep deprivation is accumulative; after ten consecutive days of seven hours of sleep, our brains are as dysfunctional as they would be after going without sleep for an entire twenty-four-hour period. We refer to this process of accumulating fatigue as sleep debt. Even three full nights of increased sleeping time will not fully restore our performance after a week of slightly reduced sleep.

Concentration isn’t the only victim of sleeping too little. Sleeping less than an optimal amount stokes feelings of hunger and leads to an increased appetite. We also crave high energy (sugary) foods to offset our low energy levels. Combine this with more impulsive decision making and increased food consumption – especially high calorie foods – and it becomes clear why obesity is so closely linked to lack of sleep.

Studies indicate that sleep also plays a vital role in the robustness of our immune system. Getting sufficient hours of high-quality sleep enables a well-balanced immune defence that features strong innate and adaptive immunity, efficient response to vaccines, and less severe allergic reactions.

Sleep can even have a profound impact on fertility. One study limited a group of healthy American males to five hours of sleep per night and monitored testosterone levels over the course of a week. After just seven nights, testosterone relative to their starting baseline levels had declined by a staggering amount – enough to effectively age the participants by ten to fifteen years in terms of testosterone virility.

Lack of sleep will also manifest itself physically. For those interested in performance, sleeping less than eight hours – and especially six – per night will result in a host of physical limitations. Aerobic output will be significantly reduced, and time to physical exhaustion will drop by ten to thirty percent. Vertical jump, limb extension force, peak and sustained muscular output will all decrease. Lactic acid will accumulate at an increased rate, and blood oxygen saturation will be reduced. Even our ability to sweat – and therefore effectively cool our body – is impaired by sleep deprivation. 

For a clear illustration of the impact of even moderate sleep deprivation, consider the annual switch to Daylight Savings Time. In the Northern Hemisphere, we move the clocks forward by one hour in March to make better use of available daylight, which results in most people losing one hour of sleep. The following day brings a significant surge in heart attacks (lack of sleep causes higher blood pressure) and traffic accidents (sleep deprivation devastates our ability to concentrate). Amazingly, when clocks are moved back in the Autumn – handing us an additional hour of sleep – this trend is reversed, with both heart attacks and traffic accidents plummeting.

The take home point: if you are looking to improve your health and wellbeing, sleep is a great place to start!

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READ PART 2 of our Sleep blog: ‘How Well Do You Sleep?’

Robbie Price | Aristos Owner & Coach