acute or short-term insomnia symptoms may also produce si gnificant distress and inter-
fere with social, personal, and occupational functioning. When such symptoms are fre-
quent enough and meet all other criteria exce pt for the 3-month duration, a diagnosis of
other specified insomnia disorder or unspecified insomnia disorder is made.
Delayed sleep phase and shift work types of circadian rhythm sleep-wake disorder.
Individuals with the delayed sleep phase type of circadian rhythm sl eep-wake disorder re-
port sleep-onset insomnia only when they try to  sleep at socially normal times, but they do
not report difficulty falling asleep or stayin g asleep when their bed and rising times are
delayed and coincide with thei r endogenous circadian rhythm. Shift work type differs from
insomnia disorder by the history of recent shift work. 
Restless legs syndrome. Restless legs syndrome often produces difficulties initiating
and maintaining sleep. However, an urge to move the legs and any accompanying unpleas-
ant leg sensations are features that differentiate this disorder fr om insomnia disorder. 
Breathing-related sleep disorders. Most individuals with a breathing-related sleep dis-
order have a history of loud snoring, breath ing pauses during sleep, and excessive daytime
sleepiness. Nonetheless, as many as 50% of individuals with sleep apnea may also report
insomnia symptoms, a feature that is more  common among females and older adults.
Narcolepsy. Narcolepsy may cause insomnia complaints but is distinguished from in-
somnia disorder by the predominance of sy mptoms of excessive daytime sleepiness, cat-
aplexy, sleep paralysis, and sleep-related hallucinations.
Parasomnias. Parasomnias are characterized by a comp laint of unusual behavior or events
during sleep that may lead to intermittent  awakenings and difficulty resuming sleep.