How to get adequate or restorative sleep

Sleep is a naturally recurring state characterized by reduced or lacking consciousness, relatively suspended sensory activity, and inactivity of nearly all voluntary muscles

(the need for sleep as a function of the amount of time elapsed since the last adequate sleep episode) must be balanced against the circadian element for satisfactory sleep

get a good nights sleep. Sleep problems such as sleep apnea, sleep deprivation, insomnia, restless leg syndrome, snoring, sleepwalking, and moreThe importance of sleep is underscored by the symptoms experienced by those suffering from sleep problems. People suffering from sleep disorders do not get adequate or restorative sleep, and sleep deprivation is associated with a number of both physical and emotional disturbances. In addition, sleep is influenced by the circadian rhythms (regular body changes in mental and physical characteristics that occur in the course of about 24 hours).

Sleep typically occurs in cycles that range from 90 to 120 minutes in length, with 4-5 cycles occurring during each night's sleep. In the first half of the night, there is a transition from wakefulness into stage N1 sleep, then to stages N2, and N3. Stages N2 and N3 then reappear, followed by the first instance of REM sleep. Cycles of stage N2 and REM sleep alternate with each other for the second half of the night.