Motor reactivity, pain threshold and effects of sleep deprivation in unipolar depressives.

The authors studied the motor reactivity by means of serial choice reaction, electromyography of simple reactions, and defense reflexes in normal and in depressed patients. Significant differences were observed between normal and depressed patients, especially in those with retardation. The 'retarded' depressives exhibited higher pain threshold values, a lower number of motor reactions, and more prolonged reaction times. 2 normal and 4 depressed patients were submitted to the same tests after 1 night's total sleep deprivation. In normals negative effects were found in the levels of vigilance and endurance. In depressed patients, at variance with normals, the number of motor reactions increased, the reaction time decreased, and the rate of basal motor innervation improved, tending to normalization. On the contrary, pain threshold underwent the same type of changes as in controls. Sleep deprivation seemed to specifically reduce retardation phenomena in depressives, thus strongly improving motor reactivity.