When you think about quality sleep, it's normal to focus on how many hours you manage to get. Duration is key, but it's not the only part of the equation.
Pay attention to whether those 7 or 8 hours are truly restorative. Every night, we enter the same sleep cycle, in which different phases alternate. But if sleep is not of good quality, we often observe the same cycle restarting several times during the night, which... you guessed it - does not lead to deep and restorative sleep.
Each phase of the sleep cycle plays an important part for the mind and body, to help you wake up refreshed. Understanding this cyclical nature will help you assess whether you need to work on some things to ensure restorative sleep.
What is a sleep cycle?
Throughout the night, you go through several sleep phases, with one cycle typically lasting 90 minutes. Once you've been through all the phases, this cycle starts over.
Phase 1:
The shortest phase, lasting between 1 and 7 minutes. The body is not fully relaxed, but its activity, and that of the brain, begin to slow down. Unless someone wakes you up, you will easily transition to phase 2.
Phase 2:
Lasts between 10 and 25 minutes. The body enters a "muted" state: temperature drops, muscles relax, breathing and heart rate slow down. At the same time, brain waves show a new pattern and eye movement stops. Overall, brain activity decreases, but short bursts of activity are observed, which actually help against the resistance to waking up due to external reasons - noises, light, etc.
Phase 3:
This is a deep sleep phase, lasting between 20 and 40 minutes. It would be difficult to wake someone easily in this phase. Pulse, heart rate, and breathing rate drop even further.
Brain activity has a pattern that is harder to establish – delta waves. Experts believe that this phase is critically important for restorative sleep, improving the immune system, and other key bodily processes. Although brain activity is low, there is evidence that deep sleep aids creativity, memory, and problem-solving.
You spend most time in deep sleep in the first half of the night.
REM
During REM sleep, brain activity begins to increase, reaching levels similar to wakefulness. At the same time, the body experiences atonia, which is a temporary paralysis of the muscles with two exceptions: the eyes and the muscles controlling breathing. Although the eyes are closed, they can be seen moving rapidly, hence the name of this phase.
REM sleep is considered essential for functions such as memory, learning, and creativity. It is best known for being when the most vivid dreams occur, which explains the significant increase in brain activity. You can have dreams in any phase, but they are rarer and less intense in non-REM periods.
Why are sleep phases important?
Each has its own function and allows the body and brain to develop and recover. The inability to provide deep sleep and REM sleep can lead to poorer focus, loss of emotional control, and physical manifestations of sleep deprivation.
What affects sleep phases?
Age: phases are very different in adults, middle-aged individuals, children, and newborns. The latter spend significantly more time in REM and can enter it directly upon falling asleep. Older individuals, on the other hand, spend less time in REM.
Recent changes in sleep patterns: if you haven't been getting enough quality sleep for days, your sleep cycle will be disrupted and abnormal.
Alcohol: reduces REM sleep early in the night, and when its effect diminishes, REM sleep catches up with long REM phases.
Environment: too warm, too cold, noisy, or uncomfortable - whatever applies to you, you can adjust it relatively easily.
Sleep disorders: sleep apnea, RLS, and other conditions that can cause multiple awakenings.
How to take care of your sleep?
While we don't have complete control over our sleep phases, there are several things that can contribute to deep and healthy rest.
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