On weekdays, the French sleep an average of 6 hours and 42 minutes per night—15 minutes less than in 2023. This is according to a study by the National Institute of Sleep and Vigilance (Les Echos). This is far from the recommended 8 hours of sleep.
However, sleep is a necessary period of rest that should not be neglected, because it is during the night that the body and mind regenerate—in different ways depending on the sleep stage we are in. At night, we transition from falling asleep to light sleep and then to deep sleep.
These sleep stages alternate and repeat until you wake up. This is what is known as sleep cycles. On average, there are four to five sleep cycles per night, each lasting between 1 hour and 30 minutes and 2 hours.
Phase 1: Falling Asleep and Preparing for Sleep
Falling asleep is the first stage of sleep. It is the preparatory stage characterized by a feeling of drowsiness. The muscles relax, brain activity begins to slow down, and eye movements become slower.
Outside noises can easily make it difficult to fall asleep. A quiet environment and dim lighting make it easier to fall asleep by promoting the production of melatonin, the sleep hormone.
The Function of Sleep Onset and Its Duration
This relatively short phase prepares the body to enter deeper stages of sleep. It lasts an average of five to twenty minutes and accounts for about 5% of total sleep time.
Phase 2: Light Sleep and Processing the Day's Information
The body then enters light sleep, the longest phase of sleep. During this phase, body temperature drops, heart and breathing rates slow down, and brain activity continues to decrease.
The Functions of Light Sleep
Light sleep consolidates declarative memory—that is, the recollection of personal experiences, such as a birthday, or facts, such as an important date or a concept.
It allows the brain to sort through the day's information and decide which data to retain and which to discard. Light sleep prepares the brain for deep sleep.
The duration of light sleep
Light sleep is the longest phase of sleep, typically accounting for 50% of total sleep time. It can last between 45 and 60 minutes per cycle.
Phase 3: Deep Sleep and Physiological Recovery
Deep sleep can then begin. During the third stage of sleep, awareness of the external environment disappears.
Blood pressure drops, and breathing becomes steady and deep. At this stage, the body is less sensitive to external stimuli, and it becomes harder to wake up.
The Functions of Deep Sleep
Deep sleep plays a vital role in physical recovery and overall health.
The body repairs tissues, strengthens the immune system, and releases growth hormones that are essential for maintaining muscles and bones.
A lack of deep sleep can lead to physical fatigue, decreased performance, and increased susceptibility to illness.
The duration of deep sleep
Although this phase is very important, it accounts for only 25% of total sleep time. It can last 20 to 30 minutes per sleep cycle.
Phase 4: REM Sleep and Mental Regeneration
REM sleep is also part of deep sleep. During this phase, brain activity is intense and relatively similar to that during wakefulness. This is the time of night when dreams are most vivid.
Depending on the dream, the eyes can move very quickly beneath the eyelids, while the rest of the body is effectively paralyzed. It is this paradox that gives the condition its name.
The Functions of REM Sleep
This sleep phase promotes mental regeneration. The time spent in REM sleep enhances creativity and problem-solving skills.
It also strengthens emotional memory by sorting and stabilizing the emotions experienced in dreams, as well as procedural memory—that is, the integration of sensory perception processes, such as knowing how to play an instrument or ride a bike.
A lack of REM sleep can lead to difficulty concentrating, emotional instability, and memory problems.
The duration of REM sleep
The REM sleep phase lasts 15 to 20 minutes per cycle and accounts for 20% of total sleep time. Its duration increases as the night progresses. REM sleep is longest in the morning.
In fact, we remember the dreams we have during this phase better when we wake up. Understanding the stages of sleep helps us appreciate the importance of good sleep hygiene.
Habits such as maintaining a regular sleep schedule, creating a sleep-friendly environment, and avoiding stimulants can promote full and restorative sleep cycles.
A meditative practice such as the Yoga Nidra helps you fall asleep more easily and improves physical and mental recovery by inducing states of consciousness similar to those of deep sleep.Sleep disorders can have a significant impact on daily life and health. If you have a sleep disorder, it is important to see a doctor.