In natural settings such as near the ocean or in a forest, the level of negative ions in the air is many thousand times greater than in urban or suburban settings. Artificially creating negative ions has been shown to be an effective and fast acting treatment for depression.
It would seem to follow that spending time in natural settings might yield similar results, although it has not been demonstrated empirically.
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Research
Goel, N. Terman, M. Terman, J. Macchi, M. Stewart, J. Controlled trial of bright light and negative air ions for chronic depression. Psychological Medicine. 35(7):945-955, July 2005.
Patients were 24 (75%) women and 8 (25%) men, ages 22-65 years (mean age +/- S.D., 43.7 + 12[middle dot]4 years), with Major Depressive Disorder, Single Episode. Results: SIGH-SAD score improvement was 53.7% for bright light and 51.1% for high-density ions v. 17.0% for low-density ions. Remission rates were 50%, 50% and 0% respectively. The presence or severity of atypical symptoms did not predict response to either treatment modality, nor were phase advances to light associated with positive response. Conclusions: Both bright light and negative air ions are effective for treatment of chronic depression. Remission rates are similar to those for SAD, but without a seasonal dependency or apparent mediation by circadian rhythm phase shifts. Combination treatment with antidepressant drugs may further enhance clinical response.
Terman, M. Terman, J. Ross, D. A Controlled Trial of Timed Bright Light and Negative Air Ionization for Treatment of Winter Depression. Arch Gen Psychiatry. 1998;55:875-882.
This study used a morningxevening light crossover design balanced by parallel-group controls, in addition to a nonphotic control, negative air ionization. Subjects with seasonal affective disorder (N=158) were randomly assigned to 6 groups for 2 consecutive treatment periods, each 10 to 14 days. Light treatment sequences were morning-evening, evening-morning, morning-morning, and evening-evening (10000 lux, 30 min/d). Ion density was 2.7×106 (high) or 1.0×104 (low) ions per cubic centimeter (high-high and low-low sequences, 30 min/d in the morning).Results: Analysis of depression scale percentage change scores showed low-density ion response to be inferior to all other groups, with no other group differences. Response to evening light was reduced when preceded by treatment with morning light, the sole sequence effect. Stringent remission criteria, however, showed significantly higher response to morning than evening light, regardless of treatment sequence.Conclusions Bright light and high-density negative air ionization both appear to act as specific antidepressants in patients with seasonal affective disorder. Whether clinical improvement would be further enhanced by their use in combination, or as adjuvants to medication, awaits investigation.
Terman, M, Terman, J. Controlled Trial of Naturalistic Dawn Simulation and Negative Air Ionization for Seasonal Affective Disorder. Am J Psychiatry 163:2126-2133, December 2006
The patients were 99 adults (77 women and 22 men) with the winter seasonal pattern of major depressive disorder (94 cases) and bipolar II disorder (five cases). Five parallel groups received 1) dawn simulation (0.0003–250 lux in the pattern of May 5 at 45° north latitude); 2) a dawn light pulse (13 minutes, 250 lux, with an illuminant dose of 3.25×103 lux-minutes matched to the simulated dawn); 3) postawakening bright light (30 minutes, 10,000 lux); 4) negative air ionization at high flow rate (93 minutes, 4.5×1014 ions/second); or 5) ionization at low flow rate (93 minutes, 1.7×1011 ions/second). The symptoms were assessed over 3 weeks with the Structured Interview Guide for the Hamilton Depression Rating Scale—Seasonal Affective Disorder Version. RESULTS: Posttreatment improvement results were bright light, 57.1%; dawn simulation, 49.5%; dawn pulse, 42.7%; high-density ions, 47.9%; and low-density ions, 22.7% (significantly lower than the others). Contrary to the authors’ hypothesis, analysis of variance failed to find superiority of dawn simulation to the dawn pulse or bright light. However, the dawn pulse led to a pattern of residual or exacerbated depressive symptoms similar to those seen in low-density ion nonresponders. CONCLUSIONS: Naturalistic dawn simulation and high-density ionization are active antidepressants that do not require the effort of postawakening bright light therapy. They can be considered candidate alternatives to bright light or medication.
Goel, N. Etwaroo, G. Bright light, negative air ions and auditory stimuli produce rapid mood changes in a student population: a placebo-controlled study. Psychological Medicine. 36(9):1253-1263, September 2006.
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 (10000 lux; n = 29), auditory stimuli (60 dB; n = 30), or high-density (4.5 x 1014 ions/s flow rate; n = 29) or low-density (1.7 x 1011 ions/s; n = 30; placebo control) negative ions. Exposure was for 30min 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 (>=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.
Goel, N; Terman, M; Terman, Jiuan S; Macchi, M; Stewart, J. Controlled trial of bright light and negative air ions for chronic depression. Psychological Medicine. 35(7):945-955, July 2005.
Results: SIGH-SAD score improvement was 53[middle dot]7% for bright light and 51[middle dot]1% for high-density ions v. 17[middle dot]0% for low-density ions. Remission rates were 50%, 50% and 0% respectively. The presence or severity of atypical symptoms did not predict response to either treatment modality, nor were phase advances to light associated with positive response. Conclusions: Both bright light and negative air ions are effective for treatment of chronic depression. Remission rates are similar to those for SAD, but without a seasonal dependency or apparent mediation by circadian rhythm phase shifts. Combination treatment with antidepressant drugs may further enhance clinical response.
Krueger, A. Kotaka, S. The effects of air ions on brain levels of serotonin in mice. International Journal of Biometeorology. Volume 13, Number 1 / June, 1969.
Mice were maintained in a controlled pollutant-free microenvironment and were exposed for 12, 24, 48 and 72 hr to 3 different concentrations of small positive or negative air ions: 2–4 × 10^3 ions/cm3, 3–4 × 10^4 ions/cm3 or 3.5–5 × 10^5 ions/cm3. Spectrophotofluorometric assays of brain serotonin levels of air ion-treated mice showed statistically significant differences as early as 12 hours from those of mice kept in untreated pollutant-free air. They did not persist after 12 hours.
Morton, L. Kershner, J. Differential negative air ion effects on learning disabled and normal-achieving children. International Journal of Biometeorology. Volume 34, Number 1 / March, 1990.
Forty normal-achieving and 33 learning disabled (LD) children were assigned randomly to either a negative ion or placebo test condition. On a dichotic listening task using consonant-vowel (CV) combinations, both groups showed an ion induced increase in the normal right ear advantage (REA).
