Treatment is justified if it has significantly improved their wellbeing and function. A combination of medication with psychological techniques is likely to be most beneficial, especially for resistant cases. Sleep disorders NORMAL SLEEP Humans spend about a third of the time asleep but why we sleep is not yet fully understood. Sleep is a state of inactivity accompanied by loss of awareness and a markedly reduced responsiveness to environmental stimuli. When a recording is made of the electroencephalogram (EEG) and other physiological variables such as muscle activity and eye movements during sleep (a technique called polysomnography), a pattern of sleep emerges, consisting of. | treatment is justified if it has significantly improved their wellbeing and function. A combination of medication with psychological techniques is likely to be most beneficial especially for resistant cases. Sleep disorders NORMAL SLEEP Humans spend about a third of the time asleep but why we sleep is not yet fully understood. Sleep is a state of inactivity accompanied by loss of awareness and a markedly reduced responsiveness to environmental stimuli. When a recording is made of the electroencephalogram EEG and other physiological variables such as muscle activity and eye movements during sleep a technique called polysomnography a pattern of sleep emerges consisting of five different stages. This pattern varies from person to person but usually consists of four or five cycles of quiet sleep alternating with paradoxical or active rapid eye movement REM sleep with longer periods of paradoxical sleep in the latter half of the night. A representation of these stages and cycles over time is known as a hypnogram and one derived from a normal subject appears in Figure with paradoxical sleep depicted as the shaded areas. SLEEP DISORDERS 19 Quiet sleep is further divided into four stages each with a characteristic EEG appearance during which there is progressive relaxation of the muscles and slower more regular breathing as the deeper stages are reached. Most sleep in these deeper stages occurs in the first half of the night. During paradoxical sleep the EEG appearance is similar to that of waking or drowsiness. There is irregular breathing complete loss of tone of the skeletal muscles and frequent phasic movements particularly of the eyes consisting of conjugate movements which are mostly lateral but can also be vertical hence the term rapid eye movement sleep most dreaming takes place in this stage. The length of total sleep in a day varies between 3 and 10 hours in normal subjects with an average in the 20-45 year age group of 7-8 h. Sleep time is decreased in .
