Bright light, negative air ions and auditory stimuli produce rapid mood changes in a student population: a placebo-controlled study

Jun 8, 2006Psychological medicine

Bright light, negative air ions, and sounds quickly change mood in students compared to placebo

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Abstract

Exposure to bright light, auditory stimuli, and high-density negative ions resulted in rapid mood improvements in 118 participants.

Active stimuli reduced depression, total mood disturbance, and/or anger within 15-30 minutes compared to the low-density placebo.
Bright light was tested at 10,000 lux, and auditory stimuli were presented at 60 dB.
High-density negative ions were delivered at a flow rate of 4.5x10(14) ions/s.
The study included both mildly depressed and non-depressed adults, with no significant differences in response based on depressive symptoms or testing season.
Effect sizes for mood changes were small to medium.

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BACKGROUND: Bright light and high-density negative air ion exposure are efficacious for winter and non-seasonal depression compared with a low-density negative ion placebo. Similarly, auditory stimuli improve mood in clinical populations. This study compared the short-term effects of bright light, an auditory stimulus, and high- and low-density negative ions on mood and alertness in mildly depressed and non-depressed adults.

METHOD: One hundred and eighteen subjects, 69 women and 49 men (mean age+/-S.D., 19.4+/-1.7 years), participated once across the year. Subjects were randomly assigned to one of four conditions: bright light (10,000 lux; n=29), auditory stimuli (60 dB; n=30), or high-density (4.5x10(14) ions/s flow rate; n=29) or low-density (1.7x10(11) ions/s; n=30; placebo control) negative ions. Exposure was for 30 min on three consecutive evenings between 1900 and 2100 hours. Mood and alertness assessments, using standardized scales, occurred before, and 15 and 30 min during exposure. The Beck Depression Inventory classified subjects as depressed (> or =10; n=35) or non-depressed (<10; n=83).

RESULTS: The three active stimuli, but not the low-density placebo, reduced depression, total mood disturbance (a global affect measure) and/or anger within 15-30 min. Neither testing season nor degree of depressive symptoms affected response to stimuli.

CONCLUSIONS: The auditory stimulus, bright light and high-density ions all produced rapid mood changes - with small to medium effect sizes - in depressed and non-depressed subjects, compared with the low-density placebo, despite equivalent pre-study expectations. Thus, these stimuli improve mood acutely in a student sample, including a subset with depressive symptoms.

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Bright light, negative air ions and auditory stimuli produce rapid mood changes in a student population: a placebo-controlled study

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