Profiles of Subjective Daytime Sleepiness through Cluster Analysis.

Sleepiness propensity and sleepiness perception are two relevant dimensions of the general multidimensional sleepiness construct. In the current study, the aim was to identify eventual homogeneous subgroups when sleepiness propensity and sleepiness perception measures are combined. Data from 678 undergraduate students (aged 17 to 24 years) from a medical school were analyzed. A Two-Step Cluster Analysis was performed taken into consideration sleepiness propensity and sleepiness perception measures as clustering variables. Four different clusters were identified. Additionally, the two groups comprising higher levels of sleepiness perception (i.e., "high perception, low propensity" and "high subjective daytime sleepiness" clusters) had the most compromised results in some of the sleep-related variables examined - sleep needs, sleep latency, sleep quality, sleep sufficiency, self-reported insomnia, sleep reactivity to stress, and cognitive arousal - and in some of non-sleep related variables, such as neuroticism and affect. As to non-sleep variables, those groups reported higher scores in neuroticism, arousability, self-reported mental health and affective states. The identification of distinct groups concerning self-reported sleepiness may bring new avenues for research and understanding of the specific and differential role of sleepiness and its dimensions in sleep health and sleep disturbances, in particular, insomnia disorder.