Light and smell stimulus protocol reduced negative frontal EEG asymmetry and improved mood

Abstract

Light and smell have both been shown to induce beneficial changes to human psychophysiology. Bright light therapy has been shown to have a positive impact on anxiety and depression and smell has also been shown to have positive effects on mood, stress, anxiety and depression. We developed a method for the delivery of integrated light and smell stimulation to try to optimise positive psychophysiological benefit. We tested its effectiveness on a physiological measure, EEG frontal alpha asymmetry (FA) and a psychological paradigm, the POMS test, both of which have been used as a measure of emotional state and mood. Light, pleasant smell, combined light+smell and a no stimulus control were delivered for 90s while the frontal alpha asymmetry (FA) was monitored. Smell and light+smell caused significant reductions in negative FA during stimulation. Exposure to a longer 15 min nonadaptive light+smell stimulus protocol reduced negative FA and decreased negative affect (POMS). The effects were greater in the negative FA group. Both the physiological (EEG) and psychometric (POMS) data indicate that integrated light and smell stimulation can reduce negative affect and reduce a marker for anxiety/ depression. This light+smell sensory stimulation protocol could offer a safe treatment for depression/anxiety.

Keywords

• light stimulation
• bright light therapy
• smell stimulation
• eeg frontal asymmetry
• depression
• anxiety
• mood state
• poms