Physical discomfort during sleep onset may lead to cognitive arousal, which is known to prolong sleep onset latency [73, 173]. More severe (low-back) pain has a two-way relationship with sleep: pain causes sleep disturbances, which in turn increase pain [33, 125]. Sleep disturbances associated with pain include difficulty falling asleep, difficulty staying asleep, early awakening and interrupted sleep [78]. Although the through relationships between these disturbances and pain remain unknown [172], pain may be thought of as a stressor that activates and maintains areas within the central nervous system responsible for the wake state [33]. Consequently, it is not surprising that multiple surveys have confirmed impaired sleep in patients with low-back pain