@ERSpublications Four key studies clearly contradictory over the effects of temperature on sleep apnoea and it is not clear why http://ow.ly/RWg41Aficionados of 1970s and 1980s cartoons will have no trouble imagining the look of befuddlement upon our faces reminiscent of Scooby Doo's when presented with a new mystery. Normally in an editorial, one should write a nice, succinct summary of the field providing the reader with a clear but concise understanding of where we are and where we are heading. However, it is just not possible in this case. The evidence is truly befuddling. The four key studies [1][2][3][4] are not just inconsistent with respect to the effects of temperature on sleep apnoea, they are clearly contradictory and it is not clear why. So, this will be an editorial that poses more questions than it answers.The risk factors for sleep apnoea are already well described at both clinical and population levels. Age, sex and obesity all play a role, as do upper airway anatomy/physiology [5] and control of breathing [6,7], but these traditional risk factors are all measured at an individual level rather than at a household, community or city level. Many conditions, particularly in respiratory medicine, are driven by environmental factors that may exist at a household level (tobacco smoke exposure or solid fuel heating), community level (for instance, urban noise levels [8]) or municipal/city level ( pollen counts and heatwaves). Some work has identified neighbourhood as being a risk factor for poor compliance with continuous positive airway pressure therapy [9] but very few investigators have looked at what components of a neighbourhood might increase the risks of sleep apnoea itself.