Boulos MI, et al. - In order to define normative polysomnography values adjusted for age and sex, researchers performed this comprehensive meta-analysis of adult polysomnography parameters scored using recent American Academy of Sleep Medicine criteria (2007 or 2012). Overall 169 eligible studies, with 5273 participants, were included. Reduction in total sleep time by 10·1 min and in sleep efficiency by 2·1%, increase in wake after sleep onset by 9·7 min and in sleep onset latency by 1·1 min was noted for each decade of age. For the same, arousal index increased by 2·1 events per h, percentage of N1 sleep increased by 0·5%, apnea–hypopnea index increased by 1·2 events per h, mean oxygen saturation decreased by 0·6%, minimum oxygen saturation decreased by 1·8%, and periodic limb movement index increased by 1·2 events per h. In addition, attenuated rapid eye movement latency and mean oxygen saturation and greater arousal index and apnea–hypopnea index was reported in relation to every 10% increase in the percentage of male participants.