Psychological correlates of spontaneous middle ear muscle activity during sleep

Nine subjects each spent four nights in the sleep lab during which middle ear muscle activity (MEMA) was recorded in addition to standard sleep monitoring. After an adaptation night, subjects were awakened four times on each experimental night: twice from rapid eye movement sleep and twice from stage 2: once from each stage in the presence or absence of MEMA. Detailed mentation reports were obtained, coded, and rated on scales of auditory involvement, emotional activity, bizarreness, hallucinosis, and clouding. Sleep stage was a better predictor of the mental activity of the sleeper than was the presence or absence of phasic activity on the above measures. Auditory ratings were no higher following MEMA than following non-MEMA arousals, but MEMA was associated with bizarre, discontinuous sleep mentation. Theoretical implications were discussed.