Definition of insomnia
: prolonged and usually abnormal inability to get enough sleep especially due to trouble falling asleep or staying asleep
chronic insomnia Insomnia is a patient-reported problem characterized by difficulty falling asleep or difficulty maintaining sleep; ie, frequent awakenings, difficulty returning to sleep after awakenings, or awakening too early with inability to return to sleep.— Daniel J. Buysse
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Merriam-Webster unabridged
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Time Traveler for insomnia
The first known use of insomnia was in 1739
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