Cold-induced diminution of paradoxical sleep in man.

Prolonged exposure to cold produced a chronic diminution in PS (PS-hyposomnia) primarily in the tonic component of PS. No significant change occurred in the REM (phasic or obligatory) component of PS. An inverse correlation was found in the activity of the pituitary-adrenal cortical system and the level of PS. The classical rebound phenomenon that occurs after PS deprivation was not observed in this study and it is suggested that the rebound effect characteristic of PS deprivation is related not to total PS but to its phasic (obligatory) component.