Sleep physiology

Sleep physiology

What happens during sleep?

When we fall asleep our body begins a process of repair and vital cell regeneration. Some of these processes are:
Repair of damaged cells during the day
Stimulation of the immune system
Consolidation of short- and long-term memory.

Understanding the sleep cycle

An indispensable element for healthy sleep is the correct development of its phases and cycles.

Sleep is composed of four phases and REM sleep or better known as REM; All this is a cycle, we perform the order of three to five cycles per night at least, with a duration of 90 to 110 minutes each.

In each cycle, the times we remain in the NON-REM and REM phases vary, the stay in REM increases in successive cycles.

The differences that exist in each phase of sleep are found mainly in the brain activity of the person. For example, brain waves are slower in deep phases of sleep such as 3 and 4. On the other hand, in the REM phase, despite being deep sleep, brain activity resembles the waking state, in this phase is when we dream.

Sleep is a vital necessity, but if these hours of sleep are not effective, it will be useless to spend eight hours in bed.

If the REM and NREM cycles are interrupted several times during the night – either by snoring, having difficulty breathing or waking up frequently during the night – we will prevent the vital processes of regeneration of our body, negatively affecting our health in the short and long term.

What if you don’t get enough sleep?

If you do not sleep well during the night, going through the phases of sleep, REM and non-REM, you will notice the first signs of lack of rest in:

• Mood swings, irritability, depression and drowsiness.
• Slowness in reaction capacity, memory loss, lack of attention.
• Desire to eat foods rich in fats and sugars, which could lead to weight gain.


Morgenthaler TI, Kagramanov V, Hanak V, Decker PA. Complex sleep apnea syndrome: is it a unique clinical syndrome? Sleep 2006;29(9):1203–9