Association between pupillometric sleepiness measures and sleep latency derived by MSLT in clinically sleepy patients.

Objectives The multiple sleep latency test (MSLT) has been employed extensively in clinical and research settings as a gold standard for objectively measuring sleepiness. In a general population or in a variety of work settings, however, a more convenient, rapidly administered measuring method is preferable. We examined the potential utility of pupillometry by comparing its objective measures, pupillary unrest index (PUI) and relative pupillary unrest index (RPUI), with MSLT-derived sleep latency (SL).