Sleep Cycle

I have left my books in Ceylon and sometimes I make mistakes (going by my memory which is slowly failing), in my blog posts.

Here is the summary of the Sleep Cycle. 

A book on  Sleep and Dreams is coming only after the end of the war.

My gut feeling and understanding is that the war would come to an end within 3 months and not in weeks. 

Sleep Cycle

We sleep in cycles.

Each cycle is 90 to 120 minutes.

Three (3)  NREM (N1, N2 and N3) phases and 1 REM phase make a full sleep cycle.

N1  Stage 1, also called N1, is essentially when a person first falls asleep. This stage normally lasts just one to seven minutes. During N1 sleep, the body has not fully relaxed, though the body and brain activities start to slow with periods of brief movements.

N2 is Light Sleep

N3 is Deep Sleep

Memories are probably stored during deep sleep in a raw and random fashion.

NREM        =      Non Rapid Eye Movement

REM           =      Rapid Eye Movement

SCN          =      Suprachiasmatic nucleus

Suprachiasmatic nucleus regulates Diurnal Rhythm

In REM sleep memory is reorganised and redundant information is filtered off.

REM sleep is generally 25% of the total sleep and we tend to dream in REM sleep.

Memory is stored during REM.

REM starts as short bursts and as one sleeps longer REM tends to last longer.

We have 6 cycle per night.

We generally needs 8 hours of sleep out of which 4 hours of deep sleep is vital.

One need not worry about these stages  since these patterns are determined by autonomousmelatonin secretion.

Approximately 75% of sleep is spent in the NREM stages, with the majority spent in the N2 stage. A typical night's sleep consists of 4 to 6 sleep cycles, with the progression of sleep stages in the following order: N1, N2, N3, N2, REM. A complete sleep cycle takes roughly 90 to 110 minutes.

A sleep cycle is a recurring pattern of sleep stages that the body goes through during a night's sleep. Each cycle typically lasts about 90 minutes and consists of REM (rapid eye movement) and NREM sleep, with the latter further divided into stages.

A typical sleep cycle lasts about 90 minutes, but can range from 60 to 110 minutes.

Each cycle includes:

Non-REM Sleep

This phase has three stages: N1 (light sleep), N2 (slightly deeper), and N3 (deepest sleep).

REM Sleep

This is when dreaming occurs and brain activity is similar to wakefulness.

During a night's sleep, you cycle through these stages multiple times, with the deeper stages (N3) occurring more frequently in the first half of the night. The exact length of sleep cycles and the amount of time spent in each stage can vary between individuals and even from night to night for the same person.

Importance of Deep Sleep

Deep Sleep (N3) is crucial for physical restoration and is linked to the release of Growth Hormone.

REM Sleep and Dreaming

REM sleep is essential for cognitive functions like memory consolidation and emotional processing.

Most adults experience about 4-6 sleep cycles per night.

Waking Up

Brief awakenings can occur between cycles, which is normal and not necessarily a sign of poor sleep.