Periodic breathing during sleep in patients affected by fibromyalgia syndrome

Seventeen patients affected by fibromyalgia syndrome (FMS) (16 females and one male) and 17 matched healthy subjects underwent formal polysomnography, a sleep questionnaire and lung function tests. FMS patients slept significantly less efficiently than the healthy controls (p<0.01), had a higher proportion of stage 1 sleep (mean± sd , 21±6% versus 11±4%; p<0.001), less slow wave sleep (p<0.01) and twice as many arousals per hour of sleep (p<0.001). The respiratory pattern of FMS patients showed a high occurrence of periodic breathing (PB) (15±8% of total sleep time) in 15/17 patients, versus 2/17 control subjects. The short length of apnoeas and hypopnoeas did not affect the apnoea/hypopnoea index (5.1±3.5 versus 3.2±1.6; ns ), but FMS patients had a greater number of desaturations per hour of sleep (8±5 versus 3±3; p<0.01). Pulmonary volumes did not differ between the two groups, but FMS patients had a lower transfer factor of the lung for carbon monoxide ( T L,CO (5.8+1 versus 7.7+1 mmol·min ‐1 ·kPa ‐1 ; p=0.001). PB occurrence correlated with T L,CO (r=‐0.62; p=0.01), number of desaturations (r=0.76, p=0.001) and carbon dioxide tension in arterial blood ( P a,CO 2 ) (r=‐0.50; p=0.05). Stepwise multiple linear regression analysis showed desaturation frequency (p=0.0001) and T L,CO (p=0.029) to be the best predictors of PB percentage (R 2 0.73; p=0.0001). Patients complaining of daytime hypersomnolence had a higher number of tender points, about twice as many arousals per hour and a lower sleep efficiency than patients who did not report this symptom. T L,CO was more impaired and the occurrence of PB was higher. The occurrence of periodic breathing in fibromyalgia syndrome patients, which was previously unreported, and is shown to be linked to a reduction of transfer factor of the lung for carbon monoxide could play a major role in the symptoms of poor sleep of these patients.