A baby begins its sleep routine before birth, at around 7 months into the pregnancy. When a baby is born, it will need between 15 and 18 hours of sleep during the first few months and its sleep pattern will be different to that of a child or an adult. For example, the REM phase is longer in babies under 2 years of age, lasting almost 50% of the total effective sleep time, whereas the REM phase in an adult may reach 25%. The REM stage is crucial for cognitive and neural development whereas the slow-wave sleep phases (deep sleep) are related to cellular regeneration and physical recuperation.
However, these phases are not continual but maintain entry and exit cycles with around 5-6 daily phases being recorded for a baby. The REM phase is very active and seems to exacerbate any stressor or disturbance might quickly take the baby out of REM sleep, losing at least 20% of the cognitive development programmed for that night.
On the other hand, cellular (physical) regeneration and growth occur at a higher level in the other phases, with the growth hormone being one of the greatest inductors in cellular reproduction giving a clearly legible signal (pulse) after the first hour of sleep.
It is therefore essential that a baby has a full hour of the proper quality of sleep for the aforementioned to occur. Sleeping properly will allow the baby to regulate the circadian rhythm that it will have for the rest of its life, something that will be essential and will later allow the child to grow physically and cognitively. It has been shown that children deprived of the REM
phase have markedly increased levels of anxiety, aggressiveness, low performance and a poor memory. It has also been proven that sleep disorders seriously affect the endocrine system which can lead to food disorders that could result in child obesity, sleep apnea and hyperactivity. Similarly, during preadolescence or adolescence, sleep disorders or problems can lead to the appearance of bipolar disorder, substance abuse, depression and eating disorders.