# Disordered descent into sleep: microstructural divergence across arousal-linked conditions

## TL;DR

The paper explores how sleep onset differs across various sleep disorders using detailed microstructural analysis.

## Contribution

The study introduces disorder-specific signatures of arousal instability during sleep onset using Hori microstaging.

## Key findings

- Narcolepsy type 1 shows compressed and irregular sleep onset patterns.
- Fibromyalgia is associated with prolonged and divergent sleep onset.
- Idiopathic REM sleep behavior disorder and NREM parasomnia have near-normative sleep onset trajectories.

## Abstract

Sleep onset is an unstable transition whose microstructure may distinguish clinical phenotypes. Using Hori 4-second microstaging in patients with narcolepsy type 1, idiopathic REM sleep behaviour disorder, NREM parasomnia and an exploratory fibromyalgia cohort, each with matched controls (n = 48 pairs), we quantified timing, entropy, hemispheric laterality and sequence ordering. Narcolepsy showed compressed, irregular onset, fibromyalgia prolonged divergent onset, and the remaining groups near-normative trajectories, suggesting disorder-specific signatures of arousal instability.