Good Sleep, Healthy Body
As we get closer to the end of winter and the mornings start getting lighter, we can see the light at the end of the tunnel, as we count down the days to summer.  We tend to reflect over the course of the winter months on how cold, wet and miserable it has been and one of the most common phrases we hear or say is how tired we are.  This may be the result of a multitude of different factors such as increased work hours, the lack of sunlight (vitamin D) or generally being busy with families or friends.  So how does sleep, or lack of it, affect us?

What is Sleep and Its Stages?
Sleep follows a pattern of alternating REM (rapid eye movement) and NREM (non-rapid eye movement) sleep throughout a typical night, in a cycle that repeats itself about every 90 minutes.

NREM Sleep
(75% of night): As we begin to fall asleep, we enter NREM sleep, which is composed of 4 stages:

N1 (Stage 1)
During stage 1 sleep, our breathing gradually becomes more regular and our heart rate begins to slow.  Dreaming is relatively rare during this stage, but sudden twitches or jerks (sudden short micro-awakenings often accompanied by a falling sensation) are quite common.  During this short period of very light, easily disrupted sleep, usually lasting less than 10 minutes, we may be aware of sounds and conversations. If we’re woken during this period we often believe we’ve never slept at all. Typically, this stage represents only about 5% of the total sleep time.

N2 (Stage 2)
This is the first unequivocal stage of sleep.  During this phase muscle activity decreases and conscious awareness of the outside world begins to fade completely.  If any sounds are heard, we’re generally not able to understand their content.  Because we pass though this stage several times during the night, more time is spent in stage 2 sleep than in any other single stage, and it typically constitutes about 45%-50% of total sleep time for adults (or even more in young adults).

N3 (Stages 3 and/or 4)
Also known as deep or delta or slow-wave sleep (SWS), during this period as we sleep we are even less responsive to the outside environment, and unaware of any sounds or other stimuli.  Stage 3 sleep occurs in longer periods during the first half of the night, particularly during the first two sleep cycles, and represents around 15%-20% of total adult sleep time.

As well as neuronal activity, other physical indicators such as brain temperature, breathing rate, heart rate and blood pressure are all at their lowest levels during stage 3 sleep.   Dreaming is more common during this stage than in the other non-REM sleep stages, although not as common (nor as vivid and memorable) as during REM sleep.  This is also the stage during which parasomnias like night terror’s, sleep-walking, sleep-talking and bedwetting occur.  Information processing and memory consolidation also takes place during this period.  It is much more difficult to wake a person during stage 3 sleep, and if awakened at this stage they will often feel very groggy and may take up to 30 minutes before they achieve normal mental performance.  Children and young adults tend to have more stage 3 sleep than adults, and the elderly may experience little or no stage 3 sleep at all.

REM Sleep
REM sleep occurs in cycles of about 90-120 minutes throughout the night, and it accounts for up to 20-25% of total sleep time in adult humans, although the proportion decreases with age (a newborn baby may spend 80% of total sleep time in the REM stage).  In particular, REM sleep dominates the latter half of our sleep period, especially the hours before waking, and the REM component of each sleep cycle typically increases as the night goes on.

As the name suggests, it is associated with rapid (and apparently random) side-to-side movements of the closed eyes.  It is believed that the eye movements may relate to the internal visual images of the dreams that occur during REM sleep.

So how much sleep do we need?
Sleep can be considered adequate or optimal when there is no daytime sleepiness or dysfunction.  We are getting enough sleep when we feel wide awake during the day, and can perform all our daily activities without problems.  In practice, this requires a certain minimum quantity of sleep, but also a good quality of sleep, which includes spending enough time in the different stages of sleep, especially deep slow-wave non-REM sleep and REM sleep.

Sleep normally depends on our lifestyles and our age.  The National Sleep Foundation suggests that for adults (25-65 years) our golden standard of 7-9 hours of sleep a night is the most beneficial length of time. People younger than this will require more sleep and the older we become the less sleep we require.

So Why is Sleep Important?
Each sleep stage in any particular sleep cycle fulfils a distinct physiological and neurological function, each of which appears to be necessary for the health of the body and mind.

During Stage 3 NREM phase where we have our deepest sleep our bodies go through the most physiological changes.  As a physio this is the most important phase of sleep as our muscles are relaxed and blood supply to our muscles increases.  This helps with tissue repair and growth.  Essentially if we lack this phase of sleep we delay our bodies natural healing process and our return to the activities that we wish to go back to.

How do we Guarantee a Good Sleep?
I’m as guilty as the next person, flicking through endless video’s and photos on social media, when really, I should be getting an early night’s sleep. I have listed below some of the most recommended tips for getting a great sleep.

  • Stick to a sleep schedule of the same bedtime and wake up time, even on the weekends.  This helps to regulate your body’s clock and could help you fall asleep and stay asleep for the night.
  • Practice a relaxing bedtime ritual.  A relaxing, routine activity right before bedtime conducted away from bright lights helps separate your sleep time from activities that can cause excitement, stress or anxiety which can make it more difficult to fall asleep, get sound and deep sleep or remain asleep.
  • If you have trouble sleeping, avoid naps, especially in the afternoon. Power napping may help you get through the day, but if you find that you can’t fall asleep at bedtime, eliminating even short catnaps may help.
  • Exercise daily. Vigorous exercise is best, but even light exercise is better than no activity. Exercise at any time of day, but not at the expense of your sleep.
  • Design your sleep environment to establish the conditions you need for sleep. Your bedroom should be cool, free from any noise that can disturb your sleep and free from any light.
  • Sleep on a comfortable mattress and  Make sure your mattress is comfortable and supportive.  The one you have been using for years may have exceeded its life expectancy – about 9 or 10 years for most good quality mattresses.  Have comfortable pillows and make the room attractive and inviting for sleep but also free of allergens
  • Use bright light to help manage your circadian rhythms.  Avoid bright light in the evening and expose yourself to sunlight in the morning. This will keep your circadian rhythms in check.
  • Avoid alcohol, cigarettes, and heavy meals in the evening.
  • Wind down.  Your body needs time to shift into sleep mode, so spend the last hour before bed time doing a calming activity such as reading. For some people, using electronic devices before bed can make it hard to fall asleep, because the particular type of light emanating from the screens of these devices stimulates the brain.  It is best to avoid electronics before bed if you have trouble sleeping,

To look after ourselves well, not only should we be eating correctly and exercising just don’t underestimate the impact and benefits a good sleep can have on the power of healing and good health in general.

References
Sleepfoundation.org
Howsleepworks.com