The Sleep Condition Indicator and the Idiopathic Hypersomnia Severity Scale: Measurement Invariance and an Exploratory Network Approach in a French Sample of University Students.

Insomnia and hypersomnolence symptoms are prevalent among university students, yet their assessment methods face limitations, and the relationship between these symptoms remains underexplored. We examined the structural invariance of the Sleep Condition Indicator (SCI) and the Idiopathic Hypersomnia Severity Scale (IHSS) in university students. In addition, we proposed a network approach to the insomnia and hypersomnolence symptoms. A total of 433 university students underwent a clinical interview for sleep and socio-demographics and completed the SCI and the IHSS. Confirmatory factorial and network analyses were conducted. The SCI demonstrated a two-factor structure, while the IHSS exhibited a three-factor structure. Over 70% of students scored above the IHSS clinical threshold, while 36.5% were diagnosed with insomnia. For the SCI, a threshold of ≤ 13 demonstrated the highest predictive value for diagnosing insomnia. Network analyses highlighted the central role of cognitive consequences of insomnia and hypersomnolence. Cognitive and emotional consequences of insomnia and hypersomnolence were moderately interconnected. Higher cognitive complaints related to insomnia were associated with increased feelings of insufficient sleep and more pronounced sleep inertia. Additionally, greater wakefulness after sleep onset was linked to both a shorter ideal night-time sleep duration and increased difficulty staying awake during low-stimulation activities throughout the day. The SCI and IHSS showed structural invariance in university students when compared to the general population. Insomnia and hypersomnolence represent critical clinical issues among French students. We underscored the intricate relationship between insomnia and hypersomnolence, highlighting the urgent need for targeted interventions that address both daytime and nighttime sleep-wake disturbances.