You've heard that sleep works in cycles - but you don't remember anything else precisely. Maybe you recall a school lesson where it was mentioned when you were a child. Stages, phases, deep sleep or REM sleep, all words that surely mean something, but you've forgotten the order and anyway, you don't have time to read Wikipedia.
Fortunately, we're here to clearly, simply (and quickly) explain how to fall asleep - to help you gauge the quality of your sleep and open your eyes to some of your habits that might be working against you.
Drowsiness
The average sleeper's night consists of 4 to 6 sleep cycles of about 90 minutes each. During the first sleep phase, drowsiness (or "falling asleep"), you are at an intermediate stage between wakefulness and true sleep.
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Your body relaxes
Your heart rate slows down, you are less alert, and your eyes move slowly under your closed eyelids.
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This stage lasts a maximum of 20 minutes
Beyond 20 minutes of drowsiness, it is considered insomnia! To encourage your body to become drowsy in preparation for a good night’s sleep, take a look at our tip on cardiac coherence.
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If you are woken up, you won’t feel like you have slept
This is the phase where unfortunate people who fall asleep at the wheel without realizing it find themselves... so be careful to get good sleep if you have a drive ahead.
Light slow-wave sleep
As its name suggests, light sleep remains light. During this phase, your body begins to recover gently:
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Your body relaxes (even more)
Following the drowsy state, your eyes and muscles slow down even more. A noise or a light can be enough to wake you up; this is the phase during which those around you should lower the TV volume and walk quietly around the house. Your brain starts to emit slow waves.
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This stage lasts 30 to 45 minutes
It covers only 15% of total sleep time, but 50% of a cycle. As your night progresses, light slow-wave sleep decreases in favor of deep and REM sleep. The older you are, the more time you spend in this phase.
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If you are woken up, you can remember having slept
If you are a good sleeper, you have a 50% chance of thinking you stayed awake during this phase. If you have difficulty sleeping, the chance is 80%.
Deep slow-wave sleep
Deep slow-wave sleep is a phase of internal rebuilding and repair.
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You (almost) stop moving
Your body is now so relaxed that your brain emits very slow and regular electrical waves. Your heart rate and breathing slow down, and your body temperature too. It becomes very difficult to wake you, but if you do wake up, it's certain - you know you were sleeping!
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This stage lasts about 30 minutes
That is 40% of total sleep time. The older you get, the more deep slow-wave sleep time decreases.
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The time for regeneration and memory
During this phase, your body secretes somatropin, or the growth hormone (which is also secreted during exercise or stress, but produced less as you age). During childhood, this hormone helps you grow, but with age it helps you heal and strengthen your immune defenses.
Deep slow-wave sleep is also the time when your brain forms your memories. If you have good deep sleep, you will have good declarative memory (that is, the memory you can consciously access)... but beware, the opposite is also true!
REM sleep
Also called REM sleep (Rapid Eye Movement), after the twitching movements of your eyes during this sleep phase, REM sleep builds your dreams and consolidates your memory.
- Your body is both relaxed and active
REM sleep gets its name from the paradox between the total muscle relaxation typical of deep sleep, but the reactivation of the cerebral cortex which puts you in a state similar to wakefulness. Your breathing and heart rate become irregular. Your body does not respond to smells, but it can react to physical stimuli (like touch or pain).
The difference with the waking state is marked by the absence of several neurotransmitters, which are not secreted despite the activation of the cerebral cortex:
Serotonin (the happiness hormone)
Noradrenaline (a stress hormone)
Dopamine (the pleasure hormone)
Histamine (the hormone that destroys foreign substances in your body, especially in allergic reactions)
- This stage lasts from 15 to 20 minutes
With each cycle, REM sleep time increases. Like deep slow sleep, it tends to decrease with age.
- Dreams and memory
It is during REM sleep that you dream and may have restless sleep. Even though you are more likely to remember a dream you had during this sleep phase, it doesn't mean you don't dream the rest of the night - just that you never remember them! By adopting good habits, you can train yourself to remember these dreams more clearly... or even control them for an exhilarating night where all your fantasies come true. The purpose of dreams is still debated, but the scientific world is full of hypotheses on this topic that tends to fascinate the general public.
REM sleep also continues the work started by deep sleep by improving memory. By enhancing neuroplasticity, it allows for greater memory storage capacity.
For most sleepers, 7 to 8 hours is enough to recharge their batteries. But for the 10% of the world population who are "heavy sleepers," it would rather be 9 or 10 hours... As for the rare "light sleepers," they are only 5% but break all records by needing only 5 or 6 hours maximum!
No matter what, deep slow-wave sleep is always the same for everyone, about 100 minutes per night. Where light sleepers save time is on REM and light sleep - in a way, you could say light sleepers have more "concentrated" nights of sleep.
Whether you're a light or heavy sleeper, Dodow can help you gain precious minutes!
On the same topic:
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Sleep and children, a special relationship
5 positions for a good night's sleep
Learn to meditate in 5 minutes!
