After pain and fatigue, poor sleep is one of the most common symptoms of fibromyalgia (FM). Because FM has been found to affect a much higher percentage of women than men, most studies focus predominately on women. Researchers in Spain, however, developed study to compare the sleep difficulties between men and women with FM and found that men with the condition had more sleep-related respiratory problems and poorer quality of sleep than women. The study, titled “Fibromyalgia: Gender Differences and Sleep-Disordered Breathing,” was conducted by the University of Granada in Spain and published in Clinical and Experimental Rheumatology. G. Prados, lead author of the story writes, “The prevalence of FM is much lower in men than in women. Therefore, current knowledge about this chronic pain syndrome emerged mainly from research on women. The aim of the present study was to compare clinical symptoms and sleep parameters between male and female FM patients.” For the study, Prados and his team evaluated 40 FM patients (18 men and 22 women) aged 48.00±8.45 years. The participants were evaluated with questionnaires on pain, sleep, fatigue, depression, anxiety and functional impact, as well as polysomnography. Based on these evaluations, researchers found that 61% of male FM patients had an apnea-hypopnea index greater than 15, compared to 31.8% of women, and a desaturation index above five, which was twice more prevalent in men than in women. What’s more, males had poorer sleep quality (16.05±2.92% vs. 13.08±3.88%; p=0.01) and slow wave sleep (stage 3 duration: 9.02±7.84% vs. 14.44±7.32%; p=0.03) than women. No differences were found between the two groups in the level of pain, emotional distress, or daily functioning. However, pain in men, fatigue in women, and functional impact in both sexes seemed to be related to worse sleep quality. Also in women, alterations in total sleep time and rapid eye movement sleep features appeared to be related to emotional status. The study also revealed that alterations in sleep respiratory patterns were more prevalent in male than in female FM patients. More so in male FM patients, the alterations in sleep patterns, non-refreshing sleep, and other FM-related symptoms observed in this population might be part of a primary sleep-disordered breathing.