Are polysomnographic measures of sleep correlated to alexithymia? A study on laboratory adapted sleepers

Objective: Since recent findings have pointed to a correlation between alexithymia and measures of poor sleep quality during the first night of adaptation to a sleep laboratory, the aim of the current study was to assess the same relation in healthy laboratory-adapted sleepers. As a further measure of rapid eye movement (REM) sleep characteristics, REM density was also measured. Methods: Twenty-seven male subjects, without sleep or psychiatric disorders, filled out the 20-item Toronto Alexithymia Scale (TAS-20) and slept for two consecutive undisturbed nights. Polysomnography and REM density were measured in the postadaptation night. Results: Alexithymia scores did not correlate significantly with any polysomnographic variable or with REM density. Only the Externally Oriented Thinking (EOT) subscale showed a negative association with REM latency. Multiple regression on selected sleep measures as predictors confirmed these results. Conclusion: 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.