Sleep Disorders and Sleep Deprivation: An Unmet Public

Sleep Disorders and Sleep Deprivation: An Unmet Public Health Problem
http://www.nap.edu/catalog/11617.html
CONSEQUENCES OF CHRONIC SLEEP LOSS AND SLEEP DISORDERS 107
BOX 3-3
Shift Work Disorder and Jet Lag
Shift Work Disorder
Shift work type circadian rhythm sleep disorder is characterized by
complaints of insomnia or excessive sleepiness resulting from work hours
that occur during the normal sleep period, including, night shifts, early
morning shifts, and rotating shifts. Total sleep time is normally reduced
by 1 to 4 hours and sleep quality is disturbed. During work shifts individuals
can experience excessive sleepiness, reduced alertness, and
reduced performance capacity. Individuals are also commonly more irritable,
and the disorder may have negative social consequences. The
condition is closely linked to work schedules; consequently, it abates in
response to a conventional sleep schedule.
Jet Lag
Jet lag type is a temporary circadian rhythm sleep disorder that occurs
when there is a transitory mismatch between the timing of the sleepwake
cycle caused by a change in time zone. Individuals with jet lag
potentially experience disturbed sleep, decreased subjective alertness,
general malaise, somatic symptoms such as gastrointestinal disturbance,
and impaired daytime function. The severity and the duration of the symptoms
are usually dependent on the number of time zones traveled and
the direction of travel—eastern travel and travel through multiple time
zones typically result in worse symptoms than western travel.
CIRCADIAN RHYTHM SLEEP DISORDERS
Circadian rhythm sleep disorders arise from chronic alterations, disruptions,
or misalignment of the circadian clock in relation to environmental
cues and the terrestrial light-dark cycle. The 2005 update of the International
Classification of Sleep Disorders designated nine different circadian
disorders, including delayed sleep phase type, advanced sleep phase type,
nonentrained sleep-wake type, irregular sleep-wake type, shift work type,
and jet lag type (Box 3-3) (AASM, 2005). These disorders may be comorbid
with other neurological or psychiatric disorders, making the diagnosis and
treatment difficult (Reid and Zee, 2005). Diagnosis with a circadian rhythm
disorder requires meeting the following three criteria:
• Persistent or recurrent pattern of sleep disturbance due primarily to
either an alteration of the circadian timekeeping system or a misalignment
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