This study is focused on people with chronic spinal pain. To investigate the impact of sleep problems on pain and function, 45 people with chronic spinal pain and comorbid insomnia will be compared to 45 people with chronic spinal pain without insomnia.

Inclusion criteria cases:

• nonspecific spinal pain (≥3 days per week and ≥3 months of chronic low back pain, failed back surgery syndrome > 3 years prior, chronic whiplash, or chronic non traumatic neck pain)
• aged between 18 and 65 years
• seeking care because of neck pain or low back pain
• native dutch speaker
• having insomnia: in the absence of other intrinsic sleep disorders and shift work, insomnia is defined as > 30 minutes of sleep latency and/or minutes awake after sleep onset for > 3 days / week for > 6 months
• living or working within a radius of 50 km around the test location
• not starting new treatments or medication and continuing their usual care 6 weeks prior to and during study participation (to obtain steady state)
• referring from analgesics, caffeine, alcohol or nicotine in the previous 48 h of the assessments
• nonspecific failed back surgery > 3 years are permitted
• not undertaking exercise (>3 metabolic equivalents) 3 days before the experiment

Exclusion criteria cases:

• severe underlying sleep pathology (identified through baseline data of polysomnography)
• neuropathic pain
• chronic widespread pain
• being pregnant or pregnancy (including giving birth) in the preceding year
• history of specific spinal surgery
• thoracic pain in absence of neck or low back pain
• shift workers
• present clinical depression
• BMI ≥ 30

Inclusion criteria controls:

• native dutch speaking
• 18 to 65 years of age
• having chronic nonspecific chronic spinal pain (≥3 days per week and ≥3 months of chronic low back pain, failed back surgery syndrome > 3 years prior, chronic whiplash, or chronic non traumatic neck pain)
• referring from analgesics, caffeine, alcohol or nicotine in the previous 48 h of the assessments
• not undertaking exercise (>3 metabolic equivalents) 3 days before the experiment
• No new medication 6 weeks prior to the assessment
• currently not undergoing any treatment (excl. medication) for chronic spinal pain

Exclusion criteria controls:

• specific medical conditions (neuropathic pain, specific neck of back surgery, osteoporotic vertebral fractures, or rheumatologic diseases)
• chronic widespread pain syndromes (fibromyalgia or chronic fatigue syndrome)
• having insomnia (in the absence of other intrinsic sleep disorders and shift work, insomnia is defined as > 30 minutes of sleep latency and/or minutes awake after sleep onset for > 3 days / week for > 6 months)
• severe underlying sleep pathology
• being pregnant or pregnancy in the preceding year
• thoracic pain in the absence of neck or low back pain
• diagnosed depression
• BMI over 30

People with chronic spinal pain with and without comorbid insomnia (cases vs controls)