Most of us know how important it is to get agood night’s sleep for our overall health and well-being. Research has linked insufficient sleep to a greater risk of a number of chronic health conditions, from diabetes and heart disease to impaired cognitive function(1,2,3).
But most of us have also had the experience of sleeping for 7-9 hours as recommended, and still waking up feeling unrefreshed. As it turns out, getting a good night’s rest is about more than just the number of hours you spend with your head on the pillow.
There are four unique stages of sleep, and understanding how they each work and how the body and mind cycle through them can help you to optimize your shut-eye and truly reap the benefits of a good night’s sleep.
The field of research concerning sleep stages is still fairly young. Until the invention of the electroencephalogram (or EEG) in the 1950s, it was generally thought that sleep was mostly passive, and that brain activity was quite limited.
We now know that this is not the case at all! When we sleep, our bodies and minds are busy with memory consolidation, processing emotions, regulating our metabolism, rebuilding and repairing at the cellular level and detoxifying.
The sleep cycle is also intricately linked with the release and balance of hormones and chemical messengers including the “stress hormone” cortisol, growth hormone, insulin and immune system messengers called cytokines.
Each stage serves an important purpose, and spending enough time in every stage is essential for good quality sleep.
Scientists first identified five different stages of sleep, but the third and fourth stages have since been combined. Rapid Eye Movement (REM) sleep, when the brain is very active and most dreams occur, is the fourth stage. The three preceding stages are referred to as Non-REM (NREM) stages.
The first stage of sleep is brief and light, and essentially serves as a transition between being awake and being asleep. During this stage, you may still be able to hear and sense what’s going on around you.
This shallow, transitional stage of sleep generally only lasts for a few minutes(4).
As we enter stage two, we start to lose awareness of our surroundings, our breathing and heart rate normalize and body temperature drops. We’re asleep, but might be fairly easily awoken.
The second stage of sleep is considered “light” sleep, but this doesn’t make it any less necessary than the other stages. We generally spend at least half the night in stage two sleep, as the body undergoes a great deal of memory and emotional processing and general maintenance.
The third stage of non-REM sleep is referred to as deep sleep, or slow wave sleep. Being awoken by sounds or other stimuli is less likely, and if an individual is woken up during this stage, they’re likely to be groggy.
This stage of sleep is all about rebuilding and repairing. The brain is quiet, muscles are relaxed, and blood pressure and breathing rate are lower as the body focuses on restoration.
During slow wave sleep, the body releases growth hormone which helps to replenish tired muscles and tissues, as well as the hunger-regulating hormones ghrelin and leptin. This stage is also essential for the production of anti-inflammatory, immune system regulating proteins called cytokines (5)
Rapid Eye Movement (REM) sleep is marked by a significant increase in brain activity. The body is very relaxed during this stage of sleep, but the brain is at work regulating emotions and memories and clearing out anything that is unnecessary.
As the name suggests, our eyes move rapidly during REM stage sleep. This stage is also when most dreams occur.
Something that many people don’t understand about the stages of sleep is that we don’t go through them in order, and we don’t spend the same amount of time in each stage. We also don’t pass through each stage only once.
A sleep cycle, which generally lasts between 75-90 minutes, involves going through stage two sleep two or three times for every one block of time spent in deep sleep or REM sleep.
The body knows how much deep sleep it needs (this depends on several individual factors, including age). Once it’s had enough, the body will focus on moving between REM and light sleep.
If your sleep time is much too short, you may not get enough deep sleep. If your total sleep duration is just a little bit too short, what you’ll largely be depriving yourself of is REM sleep, which is essential for healthy brain function.
Even when your diet and habits are optimized for sleep quality, it can be difficult to achieve restful, restorative sleep every night. For additional support, high-quality, science-backed supplements should be considered.
There are a number of clinically proveningredients that can promote restful sleep and REM sleep without leaving you groggy in the morning, especially when combined in asynergistic formula. Herbs like chamomile and valerian root have been shown to help relax the body and mind, while vitamins like P5P (the active form of vitamin B6) can work with enzymes and hormones to enhance sleep quality, and the natural hormone melatonin can help to regulate the sleep cycle.
Another supplement that can enhance sleep quality ismagnesium bisglycinate. Magnesium may help with sleep by regulating the sleep hormone melatonin as well as through its ability to bind to the inhibitory neurotransmitter GABA (Gamma-Aminobutyric Acid). Magnesium bisglycinate offers many other whole-body benefits, and is often recommended as a daily supplement for those with or without difficulty sleeping.
When we sleep, our bodies and minds are hard at work rebuilding, repairing, detoxifying and processing memories and emotions. Each of the three non-REM (NREM) stages as well as REM sleep serve unique and important purposes.
Understanding the four stages of sleep and how to optimize your sleep cycle can lead to a better night’s rest, which has innumerable benefits for the body and mind.
Sleep quality can be enhanced with the help of diet and lifestyle modifications, as well as the use of high quality, research-backedsupplements.
Ellie Ellias - Contributing Writer, Physician's Choice