<unk>  can be a symptom of a number of factors and disorders. Specialists in sleep medicine are trained to diagnose them. Some are: * insufficient quality or quantity of night time sleep; * misalignments of the body's circadian pacemaker with the environment (e.g., jet lag, shift work, or other circadian rhythm sleep disorders); * another underlying sleep disorder, such as narcolepsy, sleep apnea, idiopathic hypersomnia, or restless legs syndrome; * disorders such as clinical depression or atypical depression; * tumors, head trauma, anemia, kidney failure, hypothyroidism, or an injury to the central nervous system; * drug abuse; * genetic predisposition; * vitamin deficiency, such as biotin deficiency; and * particular classes of prescription and over-the-counter medication.
Excessive daytime sleepiness
Hypersomnia
Irregular sleep–wake rhythm
Dyssomnia
Orthosomnia
Sleepwalking
Fidgeting
Parasomnia