According to the classification of professor H.F.R Pretchtl, named States I, II, III, IV, V.
1. Quiet sleep : stable sleep of approximately 20 minutes, the baby is motionless, eyes shut, facial expression is reduced to suction to express hunger of could be absent. Breathing is slow and steady.
2. REM Sleep : unstable sleep lasting between 10 and 45 minutes where the baby moves his upper and lower members and makes many facial expressions and has a low corporal tone. His breathing is quick and fluctuant with a quicker heartbeat (up to 160bpm) comparable to the paradoxal sleep of an adult.
3. Calm awakening: peaceful awakening not exceeding 5 minutes the first few days and reaching up to 30 minutes after a month and 2hours after 3 months. It is a moment of exchange between the environment and the child, who, with his eyes wide open actively explores his surroundings without much corporal movement.
4. Agitated awakening : the child curls up and can give the impression he is not well, he moans, frowns, has an unusual breathing rhythm and quick heartbeats.
5. Very agitated awakening : this is the escalation of the previous state ; the baby cries, gets upset and may become momentarily inconsolable.