It seems to be the general rule of thumb that we should be awake for 16 to 18 hours per day and sleep anywhere from between 6 to 8 hours in order to function properly. In the busy world that we live in today roughly half of us Brits are only getting a rather worrying 6 hours of sleep or less, and 4 out of 5 of us are suffering from ‘toxic sleep’ – sleep that is disturbed or leaves you feeling tired the following morning. Sound familiar? I know it does to me.1 In fact interuppted sleep can be just as detrimental to your health as a lack of sleep.2
Deep sleep is the most important stage of sleep as it is when your body repairs and grows new tissue, boosts the immune system, and restores energy for the following day ahead.
Although you may feel okay now you will most likely be suffering from chronic sleep deprivation which can carry with it a whole host of health risks. There are some really simple sleep solutions though; from buying a new mattress, exercising earlier in the day, to cutting down the screen time – but what if you are getting your full 8 hours and still feeling lethargic? Do you ever wonder why sometimes you wake up after having less than 8 hours sleep feeling amazing but on other days where you’ve had your full 8 you can barely reach for your alarm? In order to understand how much sleep you need and what makes your sleep ‘toxic’ firstly we must understand the stages of sleep.
Understanding Your Sleep Cycle
There are 4 stages of sleep, each cycle lasts around 90 minutes and repeats itself 4 to 6 times. We need to experience all 4 stages in order to wake up well rested – Stages 1-3 are known as NREM (non-REM) and should last between 4 to 7 hours and Stage 4 roughly 90-120 minutes. Throughout the night your cortisol levels will reduce and then peak again increase your alertness to in order to wake you.
Let’s look at the 4 stages of sleep in more detail:
Stage 1 – Transition to Sleep
This is your transition into the world of sleep and it takes only roughly 5 minutes. This is when your eyes relax and close, your muscles in your body begin to relax, and any body movement slows down. Your brain waves alternate between alpha and theta waves which are associated with relaxation. You can be easily awoken in this stage of sleep.
Stage 2 – Light Sleep
Light sleep is your first true stage and is the onset of sleep. Your heart rate will slow down, body temperature will drop, your brain wave activity becomes much slower and your brain waves will now predominately consist of theta waves. You will disengage from your surroundings and your eye movement will stop. This stage of sleep should last roughly anywhere between 10 and 15 minutes before heading into Stage 3 sleep. Overall you will spend around 50% of your sleep cycle in a Stage 2 sleep state.
Stage 3 – Deep Sleep
Stage 3 sleep tends to occur in the first half of the night. In this stage of sleep your blood pressure will drop, blood flow to your muscles will increase, your breathing will slow, and your brain waves will transition to ‘delta waves’ which are brain waves of a high amplitude with a very low frequency of oscillation. Rather interestingly though too much delta wave activity within the brain can cause the inability to think and learn, and it can even be linked to severe cases of ADHD.6 Too little however and that much needed rejuvenation will not occur.
You will be incredibly hard to awaken in Stage 3 sleep and if you do wake up you will be very groggy due to the low activity levels in your body. Deep sleep is the most important stage of sleep as it is when your body repairs and grows new tissue, boosts the immune system, and restores energy for the following day ahead. Your body releases human growth hormones (HGH) when you are in a deep sleep which is what it uses to repair itself, develop your muscles, as well as being essential to overall growth and development. This is particularly important to babies, children, and teenagers.
It is in this stage of sleep that children can experience night terrors, bed wetting, and sleepwalking. Your deep sleep should make up around 25-30% of your overall sleeping pattern.
Stage 4 – REM Sleep (or ‘Dream Sleep’)
The majority of REM sleep occurs in the second half of the night, about 90 minutes after you first fall asleep, and it is where your eyes move rapidly and jerk back and forth – also known as REM or ‘Rapid Eye Movement’. Your breathing becomes irregular, rapid, and shallow, your heart rate and blood pressure increases, and the muscles of your limbs become temporarily paralyzed (postural atonia).
As you enter REM sleep your brain waves will become faster and irregular, transitioning into those similar to the level of activity to that of when you are awake. These brain waves are known as beta waves. Beta waves are responsible for conscious thought, logic, memory, and problem solving. This increased brain activity and REM is what creates your dreams, your dreams can last anywhere from a few seconds to 30 minutes and you may only remember them if you awake during REM sleep. Your first REM cycle lasts only 10 minutes however your last cycle can last up to 1 hour.
This stage of sleep is just as important as deep sleep. REM sleep provides energy to your brain, it processes all of the information from the day, it strengthens and develops your memory, and it also replenishes the neurotransmitters dopamine and serotonin – both of which regulate your mood. A lack of REM sleep will inevitably lead to problems with mental health.
Adults should spend around 20% of their sleep cycle in REM sleep (although with age this decreases) whereas infants and children should spend around 50%.
Do you track your sleep using a sleep tracker or have you any thoughts on your own sleep patterns? Leave a comment using the comments box below. Take a look at my follow-up article ‘How to Improve the Quality of Your Sleep‘ for some top sleeping tips.
- Artis, L.. (2011). Toxic Sleep: The Silent Epidemic. In The Sleep Council. Retrieved from http://www.sleepcouncil.org.uk/2011/03/toxic-sleep-the-silent-epidemic/
- Mercola, J.. (2014). Study: Interrupted Sleep May Be as Harmful as No Sleep at All. In Mercola.com. Retrieved from http://articles.mercola.com/sites/articles/archive/2014/07/24/interrupted-sleep.aspx
- (Anonymous). (n.d.). Stages of Sleep. In Sleepdex. Retrieved from http://www.sleepdex.org/stages.htm
- (Anonymous). (n.d.). How Much Sleep Do You Need? In HelpGuide.org. Retrieved from http://www.helpguide.org/articles/sleep/how-much-sleep-do-you-need.htm
- (Anonymous). (n.d.). Brainwave frequencies during waking, REM, and non-REM sleep. Retrieved September 21, 2015, from http://soundersleep.com/uploads/waves2(w%20pics).pdf
- (Anonymous). (n.d.). 5 Types of Brain Waves Frequencies: Gamma, Beta, Alpha, Theta, Delta. In Mental Health Daily. Retrieved from http://mentalhealthdaily.com/2014/04/15/5-types-of-brain-waves-frequencies-gamma-beta-alpha-theta-delta/
- (Anonymous). (n.d.). Touch: A great night’s sleep can depend on the comfort you feel in your bedroom environment. In National Sleep Foundation. Retrieved from https://sleepfoundation.org/bedroom/touch.php