Sleep perception and the multiple sleep latency test in patients with primary insomnia

The purpose of this study was to examine the relationship between overnight sleep perception and the daytime multiple sleep latency test (MSLT) among individuals who were primary insomnia patients (PIPs) or good sleeper controls (GSCs). We collected overnight sleep data via polysomnography (PSG), subjective sleep data via a morning questionnaire (self-evaluated) and MSLT data via four 20-min naps over 8 h. Subjects included 122 PIPs and 48 GSCs. Sleep perception was calculated as subjective sleep time/objective sleep time x 100%. PIPs showed a significant difference (P < 0.001) between sleep time, as determined by PSG (387.8 +/- 100 min) and self-report (226.3 +/- 160 min), but no difference was obtained for GSCs (440.6 +/- 53 versus 435.4 +/- 65 min). The means for sleep perception were 56.4 +/- 38.8% for the PIPs and 99.3 +/- 13.6% for the GSCs (P < 0.001). In the PIPs group, weak but statistically significant negative correlations (r: -0.20 to -0.25) were found for MSLT versus sleep perception and versus self- and PSG-evaluated sleep time. Compared to PIPs with low scores on the MSLT, those with high scores had less sleep perception (%), less self- and PSG-evaluated sleep time and greater sleep misperception time. GSCs did not show significant correlations between MSLT and sleep measures or differences in comparisons between individuals with high and low scores on the MSLT. These results add novel data to the literature by suggesting that 24-h hyperarousal potentially plays a key role in the pathophysiological issues of insomnia.