In a single night, we don’t simply fall asleep and wake up —
the body gradually moves through several rhythms of rest
before circling back to begin again.
AWAKE
NON-REM 1
NON-REM 2
NON-REM 3
REMWhen we sleep, the body doesn’t stay in one state all night. It gradually moves from light sleep into deep sleep, then into REM, before starting a new cycle again.
This cycle is called the Sleep Cycle. It is made up of two main kinds of sleep, Non-REM and REM, with Non-REM divided into three stages, each with its own pattern of body and brain activity.
Over one night we pass through these cycles several times, and they aren’t always the same length. The first few usually last about 80–100 minutes, while later ones may lengthen to about 90–120 minutes. There tends to be more deep sleep early in the night, while REM gradually lengthens toward morning.
The phase in which sleep gradually deepens, step by step, from light sleep to deep sleep, across three stages. The heart and breathing slow, the muscles relax, and the body uses this time for processes involving tissue repair, the immune system and certain hormones.
The phase in which brain activity rises again to a level close to being awake. The eyes move rapidly, and dreams usually happen during this time. It is linked to learning, memory and emotional processing.
That is why sleep quality doesn’t depend on the number of hours alone. It also depends on how continuous sleep is, and on the body having the chance to move through each stage naturally.
Sleep doesn’t happen all at once. It is a gradual descent from wakefulness, through light sleep and deep sleep, to a phase in which the brain becomes almost as active as when we’re awake. Each stage has its own role, and together they run continuously as a single cycle.
This is the threshold between waking and sleeping. The body begins to relax and the heart and breathing gradually slow, but we can still wake up easily.
Sometimes you may feel a sudden jerk, or a sensation of falling, which can happen as sleep begins.
This stage may be short, but it is like the first door, leading the body out of wakefulness and into rest.
In Non-REM 2, the body responds less and less to its surroundings.
Body temperature begins to drop, the heart and breathing slow, and the brain gradually shifts into a steadier pattern of sleep.
On many nights this stage takes up most of our sleep, and it is an important bridge before deep sleep.
This is when the body reaches its deepest level of rest. The heart and breathing slow considerably, the muscles relax, and it is harder to be woken than at other times.
During this stage the body carries out processes related to tissue repair, physical recovery and efficient use of energy, as well as processes linked to the immune system and certain hormones.
Deep sleep tends to occur most early in the night and gradually decreases as the night goes on.
After the Non-REM stages, we enter REM sleep.
In this phase brain activity rises again, the eyes move rapidly, and dreams often occur vividly.
Most of the body’s muscles temporarily move much less, while muscles essential to life, such as the heart and the diaphragm, keep working.
REM is linked to learning, memory and emotional processing, and REM periods tend to lengthen toward morning.
On some nights we may sleep for many hours, yet wake up feeling as if we haven’t rested enough. One reason is that sleep quality isn’t measured by time alone — how continuous sleep is, and passing through each stage of the Sleep Cycle, matter too.
Deep sleep is linked to the body’s recovery processes — for tissues, muscles and other systems. If sleep is often disrupted, these processes may not take place fully.
Sleep is linked to learning, memory and concentration. Without enough rest, we may feel slower in our thinking, find it harder to focus, or feel that our mind isn’t yet refreshed.
Insufficient or disrupted sleep may make it harder for us to cope with stress, and may affect our mood the next day.
Even after many hours of sleep, if sleep isn’t continuous we may still feel sleepy, groggy or sluggish, which may affect work and driving.
If it continues over time, insufficient or poor-quality sleep is associated with an increased risk of several chronic diseases, such as obesity, diabetes, high blood pressure, heart disease and stroke.
We can’t make ourselves fall asleep on command, but we can gradually create conditions that help the body recognise it is time to rest.
Try to go to bed and wake up at around the same times each day, so your body clock can gradually learn its own rhythm.
Caffeine is a stimulant, and its effects can last for many hours. If you are sensitive to caffeine, avoid it in the afternoon or evening.
Light from screens and artificial light at night can interfere with the signals that tell the body bedtime is near. Try lowering the brightness and putting your screen down for a while before bed.
A quiet, cool and dark room helps reduce disturbances around you and creates an atmosphere better suited to sleep.
Take a warm bath, read, practise breathing, or do something gentle that helps the mind slow down, so you can gradually move from the rhythm of the day into the rhythm of rest.
Sleep is something the body does naturally, and we don’t need to control every stage of it. What we can do is give ourselves enough time to rest, reduce disturbances, and create surroundings that let the body move through each stage of sleep without interruption.
Good sleep
isn’t just about getting enough hoursIt’s about letting the body
move gently through each rhythm of rest
without interruption
