[Note: In Stage 1 sleep the brain transitions from alpha waves (waking) to theta waves (drowsy) and conscious awareness lowers. During Stage 2 or light sleep, muscular tone/activity lowers and conscious awareness disappears. It normally accounts for 45% to 55% of total sleep and is followed by stage 3 slow-wave sleep and stage 4 deepest slow wave sleep.]
Objective: To determine whether previously described sleep stage dynamics, reflecting the mean duration of specific sleep stages, may have clinical utility in a sample of patients with Fibromyalgia syndrome (FMS) and controls.
Methods: Women with FMS (n=15, screened to exclude other sleep disorders) and age-matched women in good health (n=15) were studied with nocturnal polysomnography, multiple sleep latency tests, 2-week pain diaries, and a measure of current pain intensity.
Results: The FMS subjects, in comparison to controls, did not show differences in several common polysomnographic measures, except for increased numbers of stage shifts (126+/-27 vs. 107+/-22, p=.042).
Mean durations for episodes of total sleep, stage 1 sleep, stage 3/4 sleep, and rapid eye movement sleep failed to distinguish FMS and control subjects (Wilcoxon rank sum tests, p>.10 for each), but those for stage 2 sleep were shorter in the FMS subjects (p=.006), possibly because transitions to stage 3/4 sleep occurred more quickly (p=.036).
Shorter stage 2 sleep durations predicted higher pain diary scores (Spearman rho=-.56, p=.0014) and current pain intensity (rho=-.71, p<0.0001) [probability that difference occurred by chance, less than 1 in 10,000].
Conclusions: Sleep stage dynamic, and, more specifically, shorter durations of sleep stage 2 periods, distinguish FMS and control female subjects and may predict pain levels experienced in FMS. Analysis of the lengths of individual sleep stages, in addition to the usual sleep stage amounts and percentages listed in standard polysomnogram reports, may have clinical utility.
Source: Sleep Medicine. Feb 29, 2008 [E-pub ahead of print] PMID: 18314389, by Burns JW, Crofford LJ, Chervin RD. Michigan Tech Research Institute, Michigan Technological University, and Sleep Disorders Center, University of Michigan, Ann Arbor, Michigan; Division of Rheumatology, University of Kentucky, Lexington, USA. [E-mail: firstname.lastname@example.org]