Fatigue, sleepiness, and physical activity in patients with multiple sclerosis
Fatigue is a frequent and disabling symptom in patients with multiple sclerosis (MS). The objective of the study was to compare fatigue and sleepiness in MS, and their relationship to physical activity. Merkelbach S, Schulz H, Kölmel HW, Gora G, Klingelhöfer J, Dachsel R, Hoffmann F, Polzer U. J Neurol. 2010 Aug 18. [Epub ahead of print]
The study compares fatigue and sleepiness in 80 patients with MS and their relationship to physical activity. Interestingly, using a combination of clinical scores, scales and questionnaires, they found sleepiness varies to an appreciable extent independently from fatigue. Sleepiness and fatigue converge for situations that demand self-paced activation, while they differ for situations in which external cues contribute to the level of activation such as watching TV or driving a car. While fatigue correlated significantly with age, the same wasn’t true with sleepiness. The perceived overlapping of fatigue and sleepiness in MS as concepts and lack of clear demarcation has proven an obstacle for research in this field. This paper goes some way to improving our understanding of these overlapping but distinct symptoms.