Further studies of scratching during sleep.

Fifteen patients with a variety of itching skin diseases (atopic eczema, dermatitis herpetiformis, lichen planus, urticaria and psoriasis) have been studied in the sleep laboratory. Recordings were made of all-night electroencephalogram, electro-oculogram, submental electromyogram, and muscle potentials from both forearms. Bouts of scratching during orthodox (NREM) sleep occurred more frequently in stages 1 and 2 than in stages 3 and 4. The frequency in paradoxial (REM) sleep was close to that in stage 2 sleep. This pattern was similar for all the diseases studied and seems to be related to the physiology of the sleep stages rather than to the skin diseases themselves. The mean duration of the bouts of scratching was not related to the sleep stage in which they started.