OBJECTIVE: To assess the effects of delta wave sleep
interruption (DWSI) on pain thresholds and fibromyalgia-like
symptoms. To examine the potential correlations between DWSI
and serum insulin-like growth factor 1 (IGF-1).
Thirteen healthy volunteers were subjected to 3 consecutive
nights of DWSI (Group 1). Pain thresholds were measured by
dolorimetry and symptoms by visual analog scale. Six subjects
not undergoing DWSI served as dolorimetry and symptom controls
(Group 2). Serum IGF-1 was measured by competitive binding
radioimmunoassay before and after DWSI.
significant differences in pain thresholds as a function of
condition (baseline, DWSI, recovery) or overnight change were
detected between or within groups (p>0.05). Morning mean
dolorimeter scores were lower than evening scores in both
groups during all 3 conditions, and were lower in Group 1 than
in Group 2 during DWSI. Group 1 subjects had higher composite
symptom scores during DWSI (p< or =0.005), attributed largely
to increases in fatigue. Serum levels of IGF-1 from Group 1
subjects showed no significant change after DWSI (p>0.05).
CONCLUSION: In our study subjects, 3 nights of DWSI caused no
significant lowering of pain thresholds compared with a
control group. Subjects appeared to have lower pain thresholds
in the mornings, and DWSI appeared to augment this effect.
Symptoms were more apparent during DWSI, but were primarily
related to fatigue. IGF-1 was not altered by 3 nights of DWSI.
The low levels of IGF-1 seen in patients with fibromyalgia
syndrome may result from chronic rather than acute DWSI, or
may be dependent on factors other than disturbances of delta