Research suggests that not just sleep position, but sleep itself, can play a role in musculoskeletal pain, including neck and shoulder pain. In one study, researchers compared musculoskeletal pain in 4,140 healthy men and women with and without sleeping problems. Sleeping problems included difficulty falling asleep, trouble staying asleep, waking early in the mornings, and non-restorative sleep. They found that people who reported moderate to severe problems in at least three of these four categories were significantly more likely to develop chronic musculoskeletal pain after one year than those who reported little or no problem with sleep. One possible explanation is that sleep disturbances disrupt the muscle relaxation and healing that normally occur during sleep. Additionally, it is well established that pain can disrupt sleep, contributing to a vicious cycle of pain disrupting sleep, and sleep problems contributing to pain.