Anirban Chatterjee
Sleep is a basic physiological need, and most of us spend about one third of our lives sleeping. Sleep architecture is composed of two basic types of sleep called rapid eye movement (REM) sleep and non-REM (NREM) sleep. NREM sleep can be further subdivided into stages , which make up different portions of the night that the individual spends sleeping. In contrast to children and adults, infants spend almost 50% of the time in REM sleep, and as much as 80% of sleep is spent in REM sleep in premature infants. Physiologically, humans are most vulnerable to changes in breathing during REM sleep, thus often classified as sleep related breathing disorders when there are associated disturbances in gas exchange. The primary sleep disorder associated with breathing abnormalities in REM sleep is obstructive sleep apnea (OSA). Different names are used to describe the spectrum of this disorder and may include upper airway resistance syndrome, sleep apnea, obstructive apnea, sleep-disordered breathing, and obstructive sleep apnea hypopnea syndrome. The focus of the following discussion will be relevant to obstructive sleep apnea. This is arguably a very important disorder in sleep medicine, as it has many serious consequences for the affected individuals, including increased morbidity and mortality and for society in general as its impact affects performance, vigilance and optimal functioning.