Monitoring Kleine-Levin Syndrome Recovery Using Human-Smartphone Interactions: A Digital Phenotyping Approach.

Kleine-Levin syndrome is a rare neurological disorder marked by recurrent hypersomnia and behavioural disturbances such as hyperphagia and hypersexuality. We report a 25-year-old Taiwanese male experiencing episodes of sleep exceeding 15 h per day. Using Rhythm, a validated smartphone app that tracks human-smartphone interactions, we monitored his sleep-wake patterns and functional changes. Inactivity during episodes and progressively structured usage during recovery reflected clinical states. Interdaily stability, a circadian rhythm metric (range: 0-1), improved from low values during episodes to > 0.37 upon return to full-time work, indicating circadian recovery. This case illustrates how digital phenotyping can longitudinally assess functional and circadian dynamics in Kleine-Levin syndrome, offering a scalable tool beyond traditional assessments.