Sleep is an ongoing, natural occurring condition of the body and brain, characterized by decreased awareness, decreased sensory behavior, decreased muscle activity and decreased interactions with external environments during rapid eye movement sleep (REMS), and decreased daytime sleepiness after the last REMS sleep episode. The quality and duration of sleep and the amount of sleep needed to establish optimal health, have been shown to depend on genetic, hormonal and neurological factors. Current sleep research is focusing on identifying modifiable risk factors that can promote sleep disorder development. One of the most studied areas is the genetic architecture of sleep disorders such as sleep apnea and insomnia. New research has focused on identifying specific genes or sets of genes that are responsible for the emergence of sleep disorders, focusing mainly on sleep related issues.
Research studies have identified specific genetic differences in the brain’s oscillatory patterns during the natural sleep/wake cycle, indicating that circadian rhythms play a critical role in determining both sleep quality and duration. Some research indicates that there are several sets of genes that control the timing of the photo-cell activity in the retina. Evidence suggests that there are different sets of genes that are required for the emergence of the N-type calcium imaging phosphodies (N-cium, beta, gamma, and delta) in the cerebrum during early visual processing and object recognition, respectively. Similarly, there are three different sets of genes that are believed to control the timing of the non-rapid eye movement sleep (NREM) sleep stage in awake human beings.
There are many theories that explain how the brain achieves sleep. One of the oldest and most widely accepted is the “culture-specific” sleep patterning theory. According to this theory, sleep emerges from a set of cultural (i.e., Western) sleep routines and associated hormones and experiences, such as the availability of melatonin and / or caffeine. It is further argued that sleep emerges from the inability of the human body to adjust to external stimuli. The culture-specific theory is particularly important for studying humans. For example, researchers found that humans are much more asleep when they are tested in Egypt than they are in the United States.
Current research suggests that the amount of sleep needed for normal cognitive performance was greater in adults than in children. In addition, adults have sleep requirements that are different from those needed by children and babies. For example, adults require more sleep (and REM sleep) to awaken from sleep than do children. The sleep requirements of adults also appear to be influenced by the amount of time they spend awake per night. Adults need about 7 hours of sleep per night, compared to the required sleep in children of the same age.
Sleep onset was always considered an accurate measure of when the human body should be awake. However, research has shown that there is an inaccuracy in the actual wake up time. The research was performed in which sleep onset was timed in newborns and adults. The results showed that both newborns and adults were actually awake at the same time. During testing, the researchers did not record the sleep onset time, but only reported the sleep depth and wake up time. There are several reasons why sleep depth and wake up times may not be reported accurately.
It is difficult to diagnose sleep apnea in newborns and older children because the signs of sleep apnea are similar and the most commonly used test is the Polysomnogram or PSG. This test only detects the presence of one of many sleep disorders such as hypotension, respiratory distress, or restless leg syndrome. Because these disorders often develop slowly over months and years, it is not possible to conclude if the baby is sleeping well or not. The PSG results are therefore not reliable in detecting sleep apnea in newborns and older children. It is important for families to monitor the sleeping patterns of their newborns and older children and report any signs of sleep apnea to their pediatrician as soon as possible.