Feasibility of an interval, inspiration-triggered nocturnal odorant application by a novel device: a patient-blinded, randomised crossover, pilot trial on mood and sleep quality of depressed female inpatients

It has been suggested that certain odorants positively affect mood, but this has not yet been scientifically tested in humans. The aim of the current study was to demonstrate the feasibility of a new odorant applicator and to assess the effects of nocturnal intermittent rose odorant application on mood, and quality of sleep and dreams in depressed female inpatients. We hypothesised that mood as primary outcome will improve. Twenty-seven normosmic, 18- to 49-year-old female, depressed inpatients were investigated in a randomised, placebo-controlled, crossover study. Exclusion criteria were rhinitis, hyp- or anosmia. During sleep, an interval-controlled, inspiration-triggered applicator added rose concentrate to the inspirated air. There were three consecutive nights of each odorant and placebo application and a wash-out phase. Patients completed standardised questionnaires on mood, dreams, and sleep quality. Four patients dropped out (n = 1: non-compliance in filling in the questionnaires, n = 3: intolerance of nasal tube). Otherwise, this novel odorant applicator was well tolerated. Application of the odorant showed no significant mood differences between rose and placebo, however, some subdomains of sleep quality and mood showed a positive trend towards improvement by rose application. The feasibility of this new device and of nasal tubes could be shown. Odorant application is well tolerated. It may have a positive influence on quality of mood and sleep in depressed patients. A longer application phase is planned to obtain convincing evidence for our hypothesis.