SLEEP CYCLES AND ALPHA-DELTA SLEEP IN FIBROMYALGIA SYNDROME

Objective. Fibromyalgia syndrome (FMS) is a musculoskeletal disorder c haracterized by generalized pain, localized tender points, chronic fat igue and nonrestorative sleep. Since sleep disturbances frequently occ ur in FMS and alpha intrusion in nonrapid eye movement (NREM) sleep pr obably associates with the nonrefreshing sleep, we prospectively studi ed the delta and alpha activity and alpha-delta ratio across sleep cyc les, performing polysomnography in 10 patients with FMS and in 14 heal thy control subjects. Methods. Night long polysomnography recordings w ere performed in all subjects. Sleep scoring was done visually accordi ng to Rechtschaffen and Kales criteria. By means of spectral analysis the conventional electroencephalogram (EEG) frequency bands were autom atically computed for the all night recordings. For alpha and delta po wer the integrated and normalized values were calculated for each slee p cycle, the evolution of these activities across successive sleep cyc les was studied. Results. Alpha-delta patterns occurred in almost all the patients who had also superficial and fragmented sleep with increa sed awakenings and reduced REM and slow wave sleep. Delta decay across sleep cycles was different in FMS and alpha activity was greater and declined, whereas the controls were persistently low throughout their sleep. Alpha-delta ratio increased progressively in successive sleep c ycles; this was again different from controls. Conclusion. Patients wi th FMS presented a high frequency of subjective sleep disturbances, an increased incidence of alpha EEG NREM sleep and clear abnormalities i n sleep cycle organization.