primary insomnia

in DSM–IV–TR, a sleep disorder characterized by difficulty in initiating or maintaining a restorative sleep to a degree in which the severity and persistence of the sleep disturbance causes clinically significant distress, impairment in a significant area of functioning, or both. The disorder is not caused by a general medical condition or the effects of a substance and is not exclusively an aspect of another sleep disorder or mental disorder. It is termed insomnia disorder in DSM–5. See dyssomnia. Compare primary hypersomnia.

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Psychology term of the day

December 22nd 2024

musical interval

the pitch or frequency spacing between two sounds. Two sounds that are an octave apart (i.e., with an interval of an octave) have a 2:1 ratio of their fundamental frequencies. See also cent.