In absence of disorders, age is the most influential factor in sleep structure so it has been used as a classifying element called sleep ontogeny.
The quality and quantity of sleep in humans varies quite significantly throughout life in both its structure and its periodicity. During the early stages of life, the human being manifested in the significant phenomenon differences regarding sleep adulthood. It is a primitive function, so that runs parallel to the embryonic development. With EEG studies have been shown, that fetuses and even sleep from the eighth month of pregnancy registries distinctions between states of sleep and wakefulness. The healthy newborns spend literally all day sleeping".
This dream of babies, called multi-or polycyclic is divided into mini-cycles from 40 to 70 minutes uninterrupted and with a high proportion of REM sleep (50%). On this age the direct transition from REM sleep to wakefulness is normal. Sleep patterns are not yet structured and the phases are not yet differentiated. It is along the first three years when consolidating nocturnal sleep of children linked to the development of the nervous system maturation. It stabilizes the time of REM and NREM, the cycle times resembles the adult pattern, establishing the differences between stages and there is a significant reduction in total sleep time. This trend continued with few changes in elderly age with a gradual decrease in time and sleep quality. During adulthood, there is a monophasic or biphasic circadian pattern set during the night. Until age 30, the total hours in bed are similar to sleep, but thereafter, sleep time decreases relative to that of hours spent in bed. Some authors have called this equation the "Sleep Efficiency Index", it is calculated by dividing the "total sleep time," TSS through"time spent in bed," TSB. In the third decade, when the progressively sleep is reduced, it shows the efficiency index.
|Sleep ontogeny - Sleep distribution by age (hours of sleep per day)|
|Newborn||8-20 hours (multiphase dream predominance of REM sleep 50%).|
|6-8 months||13-14 hours|
|2 years||12 hours|
|From 4 years to adolescence||10 hours|
|Elderly||6 hours (It reduces the quality and quantity. Increased night time awakenings, decreased sleep. REM sleep remains constant).|
The elderly results note significant changes in sleep patterns. To the elderly subjects occur more physiological changes in the pattern of sleep and associated disorders are very common at this age. The structure of sleep is fragmented with a significant increase of awakenings, and in old age this is closely linked to the occurrence of diseases, that interfere negatively with sleep (insomnia, sleep phase advance, OSAHS, disorders associated with dementia and periodic movements of the lower extremities.)