A sleep inducing system is arranged to discriminate a proper time of falling asleep on the basis of respiration cycle detected as a biological signal, and to give to human body a sleep inducing stimulus in response to the discriminated proper time. Sleep induction can be thereby attained with respect...http://www.google.es/patents/US5167610?utm_source=gb-gplus-sharePatente US5167610 - Sleep inducing system
