Sleep cycles & alpha-delta sleep in fibromyalgia (FM) syndrome

OBJECTIVE. Fibromyalgia syndrome (FMS) is a musculoskeletal disorder
characterized by generalized pain, localized tender points,
chronic fatigue and nonrestorative sleep. Since sleep
disturbances frequently occur in FMS and alpha intrusion in
nonrapid eye movement (NREM) sleep probably associates with
the nonrefreshing sleep, we prospectively studied the delta
and alpha activity and alpha-delta ratio across sleep cycles,
performing polysomnography in 10 patients with FMS and in 14
healthy control subjects.

METHODS. Night long polysomnography
recordings were performed in all subjects. Sleep scoring was
done visually according to Rechtschaffen and Kales criteria.
By means of spectral analysis the conventional
electroencephalogram (EEG) frequency bands were automatically
computed for the all night recordings. For alpha and delta
power the integrated and normalized values were calculated for
each sleep cycle, the evolution of these activities across
successive sleep cycles was studied.

RESULTS. Alpha-delta
patterns occurred in almost all the patients who had also
superficial and fragmented sleep with increased 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 cycles; this was again
different from controls.

CONCLUSION. Patients with FMS presented a high frequency
of subjective sleep disturbances, an increased incidence of
alpha EEG NREM sleep and clear abnormalities in sleep cycle

Branco J, Atalaia A, Paiva T

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