The relationship between sleep quality and perceived fatigue measured using the Neurological Fatigue Index in people with Multiple Sclerosis

Objectives: The Neurological Fatigue Index (NFI-MS) is the only known perceived fatigue scale to include questions that consider the contribution of sleep quality to symptoms of fatigue in people with multiple sclerosis (MS). However, the relationship between the NFI-MS and sleep quality measures is unknown. This study aimed to explore the relationship between the NFI-MS and self-reported and objective sleep quality. Understanding the relationship between perceived fatigue and sleep quality measures could encourage a wider use of the NFI-MS in research and clinical settings. Methods: Fifty-one participants took part in this cross-sectional study (mean age: 47 +/- 10.1 years old). Participants completed the NFI-MS to assess perceived fatigue, the Pittsburgh Sleep Quality Index to asses sleep quality, and the Epworth Sleepiness Scale to assess daytime sleepiness. The participants wore an actigraph device one week on the dominant wrist to objectively quantify sleep quality. Results: Higher perceived fatigue is significantly associated with poorer self-reported sleep quality and excessive daytime sleepiness, but not with objective sleeps quality. Discussion: The NFI-MS can be easily administered in clinical and research settings to assess the impact of sleep on perceived fatigue in the MS population.