BACKGROUND: Spinal symptoms of pain and stiffness on waking have been linked to sleep posture. Sleep posture is commonly classified as supine, side lying and prone. It is clinically postulated that sleeping postures with sustained end of range rotation and extension may influence pain sensitive spinal tissues. However, the lack of a valid and reliable method of assessing sleep posture, means clinicians are unable to provide corrective advice based upon evidenced based research. OBJECTIVE: To determine the validity and reliability of a sleep posture recording protocol in the home environment. METHOD: Twenty health professionals viewed a pre-recorded video recording of randomised sleep postures under natural and infrared light situations, with a variety of bed coverings, to represent the habitual environment. Sleep postures were classified into six categories including two intermediate postures (supported side lying and provocative side lying). Viewing was repeated after two days. RESULTS: Intra-and inter-rater reliability were excellent; Cohen’s Kappa = .93 (95% CI 0.80 to 1.0) and Fleiss Kappa = 0.83 (95% CI 0.82 to 0.84) respectively. Validity, determined as concordance between the health professionals’ classifications and the known postures, was also excellent Cohen’s Kappa = .91 (95% CI 0.77 to 1.0). CONCLUSIONS: Reliable and valid assessment of sleep posture, including intermediate postures, could be achieved using low cost, portable, infrared video recording equipment, under a variety of lighting conditions and a variety of bed cover situations typical of the home environment.