to the best of our knowledge, this study is the first to compare the sensitivity of the ICHD-3 beta criteria for " sleep apnoea headache " in OSAS patiens with morning headaches. In our study, we assessed headaches upon awakening in the morning but not headaches upon awakening during sleep or after a nap because the ICHD-3 beta criteria clearly state that a sleep apnoea headache is a morning headache caused by sleep apnoea.