Why Is Sleep So Important?
We spend approximately one-third of our lives asleep. Eight hours (sometimes) devoted to one activity where we seemingly do nothing. But is this the case?
Firstly, we need to understand what sleep is:
One definition of sleep is that it is a “a state of unconsciousness that allows your body and brain to rest” - and, although this is true to a degree, there is much about sleep we still do not know.
We know there are two phases of sleep, and that they cycle in 90 minute periods. These are Rapid Eye Movement (REM) and Non-REM (NREM) sleep. REM sleep, taking up approximately one-quarter of the sleep cycle, is characterised by random rapid eye movements, lower muscle tone and a lower overall body temperature. Also known as Paradoxical Sleep (PS) or “dreamy sleep”, REM sleep has been found to show some similarities to waking states in studies investigating brainwave activity.
NREM sleep takes up the remaining three-thirds of the sleep cycle. As the name would suggest, there is no rapid eye movement in this phase. This phase reflects a more parasympathetic (rest and digest) dominance compared to REM sleep.
But if we know so little about it, then why do we know it is important?
One thing we know happens during sleep is the body can repair itself and recover. During early sleep (hours one to three), the body releases hormones like progesterone and growth hormone. This readies the body for tissue repair and muscle growth later. REM sleep phases are shorter here as the body repairs these tissues. The brain begins to store memories in this phase.
Later (hours four to six) the body will spend longer in NREM stage two sleep as tissue repair slows; the stage is a lighter, more transitional period of sleep. Your liver is continuously filtering your blood to remove toxins, which could lead to chronic health conditions later in life if not filtered out. Your REM sleep phases become longer as the brain becomes more active, processing emotions, problem-solving and creativity.
The majority of the essential tissue repair is complete by the time we enter the final hours of sleep. The lungs begin to respiratory system of mucous and debris. The brain is still consolidating memories and integrating new information with existing knowledge to prepare you for the future.
As you sleep, the body begins to produce proteins called cytokines. These proteins are helpful in fighting infections and limiting inflammation during sickness, meaning sleep is essential for maintaining a strong immune system.
Speaking of inflammation, it has been found that consistently sleeping fewer than seven hours per night can systemic inflammation throughout the body. This inflammation has been linked to high blood pressure. So it could be said that getting the recommended amount of sleep is good for your heart.
Sleep from an MSK perspective:
Beyond the tissue repair discussed above, the connection between sleep and MSK health can be linked to several other functions.
Sleep deprivation has been linked to a decrease in our pain thresholds, which could complicate the rehabilitation process for MSK injuries - keeping you out for longer. This could create a cycle where pain then disrupts our sleep, promoting inflammation and pain which, in turn, keeps us in perceived pain.
Quality sleep is also crucial for the maintenance of muscle function. Studies have indicated that a lack of sleep reduces protein synthesis which impairs recovery of tissue, and decreases production of crucial hormones which are linked to muscle strength, power and endurance. This is particularly relevant for individuals recovering from MSK injuries, where maintaining muscle strength and function is vital for rehabilitation success.
So, what can we do to improve our sleep?
Now we understand the importance of getting good quality and prolonged sleep sessions, we can look to our own routines to see what may need improving. Below are some tips:
Sticking to a Routine - humans have circadian rhythms which act as your body’s own “clock”. This is where we associate nighttime with the time we sleep. Going to bed at similar times each night will encourage your own circadian rhythms to get you ready for bed.
Limiting Screens - it has been suggested that blue light from our phone and laptops screens can disrupt our sleep by suppressing the release the sleep hormone melatonin. Putting your phone away before you get into bed could help you fall asleep faster.
Your Bedroom Itself - Keep your bedroom cool, dark, and quiet. Blackout curtains, eye masks, and a cool temperature can make a big difference.
Manage Your Stress - Relaxation practices such as deep breathing or meditation can signal your body it is time to rest.
Sleep is not just something we get to do at the end of the day; it is an essential part of our lives. It is where your body recovers, your brain helps you remember, and you prepare yourself to perform at your best.