  While sleepiness assessment metrics were initially developed in medical
research to study the effects of drugs on sleep, subjective sleepiness
assessment is now widely used in both fundamental and applied studies. The
Stanford Sleepiness Scale (SSS) and the Karolinska Sleepiness Scale (KSS) are
often considered the gold standard in sleepiness research. However, only a few
studies have applied both scales, and their convergence and specific features
have not been sufficiently investigated. The present study aims to analyse the
dynamics and convergence of subjective sleepiness as measured by the KSS and
SSS in a population of adults. To achieve this, we present the Subjective
Sleepiness Dynamics Dataset (SSDD), which collects evening and morning data on
situational subjective sleepiness. A total of 208 adults participated in the
experiment. Our findings suggest that sleepiness generally increased from the
evening till night and was highest early in the morning. The SSS score appeared
to be more sensitive to certain factors, such as the presence of a sleep
disorder. The SSS and KSS scores strongly correlated with each other and
converged on sleepiness assessment. However, the KSS showed a more even
distribution of scores than the SSS. Currently, we are continuously expanding
the SSDD.
