The authors compared the sleep laboratory recordings of 122 drug-free
subjects who complained of chronic insomnia with the subjects' estimates of
their habitual sleep characteristics and their estimated sleep time on the
morning after sleeping in the laboratory. Most subjects consistently
underestimated the amount of time they slept and overestimated the amount
of time it took them to get to sleep in comparison with laboratory data.
All subjects consistently underestimated the number of arousals they
experienced. The authors discuss the implications of these findings for the
treatment and definition of insomnia and for further research.