34.40 Sleep and Fatigue (Alertness management)

34.40.2 Describe the stages of sleep.

Just as there are different levels of consciousness, there are different levels of sleep.

Normal sleep consists of two types:

• non rapid eye movement sleep (NREM), and
• rapid eye movement sleep (REM).

NREM sleep consists of four stages, each of which gradually merges into the next.

Stage 1:

This is a transition stage between waking and sleep that normally lasts from 1 to 7 minutes.

The person is relaxing with eyes closed.

During this time, respirations are regular, pulse is even, and the person has fleeting thoughts.

If awakened, the person will frequently say they have not been sleeping.

Stage 2:

This is the first stage of true sleep, even though the person experiences only light sleep.

It is a little harder to awaken the person.

Fragments of dreams may be experienced, and the eyes may slowly roll from side to side.

Stage 3:

This is a period of moderately deep sleep.