Effect of musculoskeletal pain on sleep architecture in patients with obstructive sleep apnea

Rationale Obstructive sleep apnea and chronic musculoskeletal pain both affect sleep. Sleep architecture of patients suffering from both is largely unknown. Objectives This study seeks to define the sleep architecture of patients with chronic musculoskeletal pain and obstructive sleep apnea. Methods Patients with obstructive sleep apnea diagnosed by sleep study during the past 3 years were included. Patients with clinical documentation of chronic musculoskeletal pain constituted cases, while others were classified as controls. Measurements Demographics, clinical factors affecting sleep, medications affecting sleep, Epworth sleepiness scores, and polysomnographic parameters; total sleep time, sleep efficiency, sleep stages, rapid eye movement (REM) sleep onset, apnea–hypopnea index, arousal index, and periodic leg movements were recorded. Results There were 393 subjects: 200 cases (obstructive sleep apnea and chronic musculoskeletal pain) and 193 controls (obstructive sleep apnea alone). There was significant difference in total sleep time (274.5 ± 62.5 vs. 302.2 ± 60.1 min, p = 0.0001), sleep efficiency (73.54 ± 15.8 vs. 78.76 ± 14.3 %, p = 0.0003), and REM sleep onset (148.18 ± 80.5 vs. 124.8 ± 70.9 min, p = 0.006). Subgroup analysis within the obstructive sleep apnea with chronic musculoskeletal pain group revealed that subjects had better total sleep time and sleep efficiency if they were on REM sleep affecting medications (suppressants and stimulants). Those on REM sleep suppressants slept 25.7 min longer and had 6.4 % more efficient sleep than those not on REM suppressants ( p = 0.0034 and p = 0.0037). Conclusion Patients with obstructive sleep apnea and chronic musculoskeletal pain sleep not only significantly less but also with inferior sleep quality. Their REM sleep is also less in duration and its onset is delayed. Despite low TST and SE, these patients may not exhibit sleepiness.