Insomnia is often co-morbid with medical or
psychiatric illness. Insomnia also has a high
co-morbidity (30-40%) with other sleep
disorders such as Obstructive sleep apnoea,
and restless legs syndrome.
Transient insomnia symptoms are common,
and may arise from stress associated with
work, finances, family, and medical and
psychiatric conditions. Insomnia is reported to
occur in 30-50% of the population in any one
year.