The sleep cycle of a newborn is similar to that of an adult except for the duration of the cycle. There are five sleep stages in the cycle, with one classified as rapid eye movement, or REM, and four as non-REM. While these stages last for 20 to 40 minutes in newborns, they take up to 90 minutes in adults. Each sleep cycle is followed by a short period of wakefulness, which often is not remembered. The sleep stages make a cycle by following this progression: wakefulness, Stages 1, 2, 3, 4, 3, 2 and REM. For a newborn, this cycle is repeated seven to nine times during the night or one to three times during a daytime nap. While waking between sleep cycles is usual, it doesn't necessary mean that your child has had enough sleep. A newborn wakes up crying between sleep cycles because her environment has changed since she fell asleep.
Stage 1
The first stage of sleep spans five to 10 minutes, during which your baby slips into a light sleep. This is deeper than drowsiness but not so deep that sudden movement or a loud noise can't wake her. This stage is marked by drooping eyelids, regular breathing and total relaxation.
Stage 2
This stage is a more comfortable light sleep stage than Stage 1. The newborn may twitch, jerk, grunt or smile, and her body temperature drops while the heart rate slows down. Sudden movement or noise can startle her and cause her to wake if too jarring. This stage can last for as long as 20 minutes or progress quickly.
Deep Sleep
Stages 3 and 4 make up the deep sleep part of the sleep cycle. They can be distinguished only by monitoring brain activity with a polygraph. Your baby is very relaxed, her breathing is slow and regular and her limbs are limp. When aroused at this point of the sleep cycle, your baby moves slowly and may even fall back to sleep.
REM Stage
Newborns spend half of their sleep in the REM stage. This stage is a light sleep stage involving increased brain activity. Dreams occur during the REM stage, and there is an increased blood flow to the brain. The REM stage is important for a newborn because it is the period when growth hormones are released. Breathing becomes erratic, and the limbs twitch. While it may seem that baby is about to wake, she really is still asleep.
