Sleep

Not only do we need enough sleep but we need good quality sleep

Did you know that every single living creature needs sleep? And by need I mean it is crucial for their existence and lack of sleep would actually mean death… But enough of the doom talk. Sleep is a fascinating phenomenon that still baffles scientists all over the world.

Read further if you want to hear some fascinating facts amongst some scientific and practical suggestions to hopefully make you have a good quality rest at night.

Sleep is an important activity we do every day as part of our routine and it can take up as much as one-third of our lifetime.  However, it is not only the quantity that is important when looking into our sleep habits but also the quality of our sleep. Doesn’t matter how much time you spend in your bed if the quality of your rest is unsatisfactory.

Ask any mum with a newborn or young child... No wonder, sleep deprivation is used as a torture technique in some places...

It is a fact, that we cannot live without sleep; just like how we cannot go on for long without food or water, sleep is essential for our survival and the quality of our lives. Although, some people wear the ‘lack of sleep’ badge as an honour to prove (to us or to themselves?) that they are incredible human beings and are better than most of us, the lack of sleep and its consequences are shockingly underrated.

I tell you a secret… There might be some super humans who can genuinely survive on 4-5 hours (regular) sleep… BUT scientists have proven that the average person needs at least 8 hours shut eye every day. Additionally, it has also been proven that the consequences of lack of sleep are as serious and dangerous as drinking (and driving). In fact, shockingly, there are more ‘sleep related’ car accidents than those caused by drink-driving.

If you wouldn’t sit behind the driving wheel after a few glasses of wine (or whatever your choice of ‘poison’ is) then why would you do so when you haven’t slept enough?

The real issue is that without sleep we cannot form and maintain the neural pathways in our brain that are necessary for us to learn and create new memories, not to mention how much harder it is to concentrate and respond quickly after a bad night.

Sleep is important to a number of brain functions, including how nerve cells (neurons) communicate with each other.  In fact, our brain and body stay remarkably active while you sleep.  Recent findings suggest that sleep plays a housekeeping role that removes toxins in your brain that build up while you are awake. 

Everyone needs sleep, but its biological purpose remains a mystery.  Sleep affects almost every type of tissue and system in the body – from the brain, heart, and lungs to metabolism, immune function, mood, and disease resistance.  Research shows that a chronic lack of sleep, or getting poor quality sleep, increases the risk of disorders including high blood pressure, cardiovascular disease, diabetes, depression, and obesity.

Stages of sleep

There are two basic types of sleep which are called (very ‘imaginatively’): 

• rapid eye movement (REM) sleep and

• non-REM sleep (with three different stages). 

Each is linked to specific brain waves and neuronal activity.  We cycle through all stages of non-REM and REM sleep several times during a typical night, with increasingly longer, deeper REM periods occurring towards the morning. 

Stage 1 non-REM sleep is the changeover from wakefulness to sleep.  During this short period (lasting several minutes) of relatively light sleep, our heartbeat, breathing, and eye movements slow, while our muscles relax with occasional twitches.  Our brain waves begin to slow from their daytime wakefulness patterns. 

Stage 2 non-REM sleep is a period of light sleep before we enter deeper sleep.  Our heartbeat and breathing slow, and muscles relax even further.  Our body temperature drops and eye movements stop.  Our brain wave activity slows down but is marked by brief bursts of electrical activity.  We spend more of our repeated sleep cycles in stage 2 sleep than in other sleep stages.

Stage 3 non-REM sleep is the period of deep sleep that we need to feel refreshed in the morning.  It occurs in longer periods during the first half of the night.  Our heartbeat and breathing slow to their lowest levels during sleep.  Our muscles are relaxed and it may be difficult to wake us up.  Brain waves become even slower. 

REM sleep first happens about 90 minutes after we fall asleep.  Our eyes move rapidly from side to side behind closed eyelids.  Surprisingly, this mixed frequency brain wave activity becomes closer to that seen in wakefulness.  Breathing becomes faster and irregular, and our heart rate and blood pressure increase to near waking levels.  Most of your dreaming occurs during REM sleep, although some can also occur in non-REM sleep.  Your arm and leg muscles become temporarily paralysed, which prevents you from acting out your dreams.  As you age, you sleep less of your time in REM sleep.  Memory consolidation most likely requires both non-REM and REM sleep.

Sleep mechanisms

There are two internal biological mechanisms working together to regulate when we are awake and asleep. These are: 

1. our circadian rhythm and

2. homeostasis.

1. Circadian rhythms direct a wide variety of functions:

• from daily fluctuations in wakefulness

• to body temperature,

• metabolism, and

• the release of hormones. 

They control our timing of sleep and cause us to be sleepy at night. It also helps us to wake in the morning without an alarm.  Our bodies’ biological clock, which is based on a roughly 24-hour day, controls most circadian rhythms.  Circadian rhythms synchronise with environmental cues (light, temperature) about the actual time of day, but they continue even in the absence of cues.

2. Sleep-wake homeostasis keeps track of your need for sleep.  The homeostatic sleep drive reminds the body to sleep after a certain time and regulates sleep intensity.  This sleep drive gets stronger every hour we are awake and causes us to sleep longer and more deeply after a period of sleep deprivation.

Factors that influence our sleep-wake needs include:

• medical conditions,

• medications,

• stress,

• sleep environment, and

• what you eat and drink. 

Perhaps the greatest influence is the exposure to light.  Specialised cells in the retinas of our eyes process light and tell the brain whether it is day or night and can advance or delay our sleep-wake cycle.  Exposure to light can make it difficult to fall asleep and return to sleep when awakened.

This is why staring at your laptop/ipad or phone before bedtime is so bad.

Night shift workers often have trouble falling asleep when they go to bed, and also have trouble staying awake at work because their natural circadian rhythm and sleep-wake cycle is disrupted. 

In the case of jet lag, circadian rhythms become out of sync with the time of day when people fly to a different time zone, creating a mismatch between their internal clock and the actual clock.