Topographical changes in N1-P2 amplitude upon awakening from sleep after SWS deprivation.

Objectives: The issue of a quantitative and qualitative impoverishment of dream activity in alexithymic subjects has been assessed by analysing the 14-day dream reports of two groups of accurately selected alexithymics and non-alexithymics. Furthermore, since recent findings pointed to a correlation between alexithymia and measures of poor sleep quality during the first night of adaptation to a sleep laboratory, the relation between alexithymia scores and polysomnographic measures was assessed by an independent study on laboratory adapted sleepers. Methods: 1st study: Ten alexithymic and 10 non-alexithymic females were selected from a larger sample of 160 undergraduate students. The transcriptions of their audio-recorded dream reports upon 14 consecutive morning awakenings were compared with regard to their length and emotional content. Self-rates obtained by a sleep and dream diary were further considered to assess between-group differences in dream recall frequency, and in its emotional valence, vividness and bizarreness. 2nd study: Twenty-seven male subjects, without sleep or psychiatric disorders, filled out the 20-item Toronto Alexithymia Scale and slept for two consecutive undisturbed nights. Polysomnography and REM density were measured in the postadaptation night. Results: Dream recall frequency and mean dream report length were lower in alexithymic as compared to non-alexithymic subjects. Emotional valence, vividness, bizarreness, emotions scored according to the Hall and Van de Castle Coding System, did not show any significant between-groups difference. The total number of emotions, scored in the dream transcriptions, showed a close-to-significance prevalence in nonalexithymics, but this difference disappeared when dream report length was partialled out. In the second study, alexithymia scores did not correlated significantly with any polysomnographic variable or with REM density. Only the Externally Oriented Thinking (EOT) subscale showed a negative association withREMlatency. Multiple regression on selected sleep measures as predictors, confirmed these results. Conclusions: Results point to a general difficulty of alexithymics in accessing (recalling) their dreams, while the failure in showing any between- group difference with respect to the emotional contents of dream mentation indicate that the difficulty in regulating affects of alexithymics should not affect dream activity. Furthermore, polysomnographic results do not extend to normal sleep the association previously found between alexithymia and a poor quality of sleep during the adaptation night in the sleep laboratory. The only polysomnographic measure showing an association, albeit little, with one facet of alexithymia was REM latency. Only quantitative aspects of dreaming, as expressed by dream recall frequency and by dream report length, clearly discriminate between alexithymics and non-alexithymics.