Background Non restorative sleep (NRS) is a characteristic symptom of fibromyalgia (FM). A number of studies have reported abnormalities of sleep architecture on polysomnography (PSG) including alpha wave intrusion (AWI) during delta wave sleep (DWS). However, AWI in DWS has also been reported in other conditions including depression or in chronic fatigue. We have compared FM patients with patients who had sleep disturbance from osteoarthritis (OA) and a group of normal healthy control subjects (NHC) to determine if there are specific abnormalities of sleep architecture in FM related to clinical parameters.
Methods We studied 19 newly diagnosed FM patients (mean age 41yrs, range 19–58yrs), 17 with OA (mean age 46yrs, range 19–63yrs) with localized pain and sleep disturbance, and ten NHC (mean age 38yrs, range 23–61yrs). All participants were female. The diagnosis was confirmed by a consultant rheumatologist. None were being treated for anxiety or depression or had taken antidepressant, psychoactive or sedative drugs for at least 2 weeks prior to analysis. All completed pain score (VAS), Brief Pain Inventory (BPI), Fatigue Severity Scale (FSS), Epworth Sleepiness Scale (EPS), Pittsburgh Sleep Quality Index (PSQI), Centre for Epidemiologic Studies Depression Scale (CESD), State and Trait Anxiety Scale (STAS), Multidimensional Scales of Health Locus of Control and Perceived Social Support (HLC), and 2 weeks actigraphy and 2 consecutive nights of polysomnography (PSG) at home, scored by a trained sleep researcher. Each frequency band was decomposed and power averaged using spectral analysis.
Results Sleep efficiency was significantly worse in FM and OA (p=0.025). Sleep stage transitions (SST) were significantly increased in FM and OA (p=0.019) with a marked increase in SST per hour (p=0.002) compared with NHC with no significant difference between FM and OA. Alpha waves were increased during stage 3 sleep (DWS) in both FM and OA compared with NHC but also with no difference between FM and OA. There was a numerical increase in spindle frequency during non REM sleep compared with NHC, more in FM than OA but with wide variation (1.12 ± 0.8; 0.98 ± 0.39; 0.61 ± 0.27 mpl). Pain scores in FM and OA groups were significantly different to NHC; mean difference in BPI of 6.07 and 4.83 respectively (p<.001). FM had significantly greater fatigue and EPS than OA (M diff14.41, p<.001; 3.42, p=.033) and NHC (M diff=29.87, p<.001; 3.99, p=0.34). PSQI was significantly greater than HC in both FM and OA (10.19 and 7.18, p<.001). The difference between FM and OA was significant (p=.023). There were highly significant differences between the 3 groups for CESD (FM 23.11; OA16.06; NHC4.8, p<0.001), STAS (49.6; 39.8; 31.9, p<0.001), HLC (p<0.001), and neuroticism (15.7; 13.5; 9.3 p<0.01).
Conclusions Patients with FM had a similar duration of sleep to this group of OA patients but had a significant difference in subjective sleep quality, with significantly increased fatigue and sleepiness. They also had more anxiety, depression and neuroticism. AWI in DWS in FM is not specific and is similar in disturbed sleep from OA, but increased spindle frequency may be a feature of FM. We hypothesise that psychological factors in FM are linked to both sleep quality and fatigue and NRS may result from an increased rate of SST with frequent fluctuation between light and deep sleep.
Disclosure of Interest None declared
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