Fluctuating bright light (10,000 lux) and synchronous smell stimulation was given to 18 subjects using light+smell goggles (see picture). They filled in a questionnaire based on the Circumplex Model of Posner et al., 2005 before and after the session registering levels of energy and mood. The results are given in the figure below. 15 minutes of fluctuating light and smell stimulation resulted in an increase in levels of both energy and mood. This type of stimulus has been demonstrated to reduce markers for anxiety and depression (Warden-Smith et al., 2017) and could be used as therapy for mood disorders (Jacob et al., 2017).
The results shown in the graph are the averaged responses (mean +/- standard error, n=18) for "mood" and "energy".