I have reached the conclusion that the human nose might be involved in cooling of the brain. In this report, I first describe the clinical observations about ankyloglossia with deviation of the epiglottis and larynx (ADEL) with regard to sleep that I have made during my 30 years of otorhino-laryngological experience. Then I describe the physiology of the nose. Next I quote from reports on paradoxical sleep, or REM sleep, from Kitamura K (2009) and Jouvet M (1992). Finally, I present the conclusion that nasal respiration is indispensable to a deep and sound sleep that refreshes humans and promotes vitality.