Mood & seasonal depression

Where the research is most encouraging.

Ionizers have been tested in controlled trials for winter depression for nearly thirty years. This is the area where the research is most developed.

58% vs 15%

responded to high-density versus low-density ions in a 25-person double-blind trial of seasonal depression (Terman & Terman, 1995).

48% vs 23%

symptom improvement with high-density versus low-density ions in a 99-person randomised trial (Terman & Terman, 2006). Bright light and dawn simulation did similarly well.

33 studies

reviewed in a 2013 meta-analysis; its depression analysis (5 studies) found lower depression ratings at high ion density.

The studies

  1. Encouraging

    Air ions and mood outcomes: a review and meta-analysis

    Perez V, Alexander DD, Bailey WH · BMC Psychiatry 13:29 · 2013

    Systematic review & meta-analysis, 33 studies

    High-density negative ionization was associated with lower depression ratings (5 studies), with a larger effect at higher exposure. No consistent effects on anxiety, mood, relaxation/sleep or comfort.

  2. Encouraging

    Controlled trial of naturalistic dawn simulation and negative air ionization for seasonal affective disorder

    Terman M, Terman JS · American Journal of Psychiatry 163(12):2126–33 · 2006

    Randomised controlled trial, n = 99

    High-density ions gave about 48% symptom improvement against about 23% for low-density (placebo) ions. Bright light and dawn simulation did similarly well.

  3. Encouraging

    A controlled trial of timed bright light and negative air ionization for treatment of winter depression

    Terman M, Terman JS, Ross DC · Archives of General Psychiatry 55:875–82 · 1998

    Randomised controlled trial

    High-density ions and bright light both acted as specific antidepressants; low-density ions did worse than all other groups.

  4. Early

    Controlled trial of bright light and negative air ions for chronic depression

    Goel N, Terman M, Terman JS, Macchi MM, Stewart JW · Psychological Medicine 35(7):945–55 · 2005

    Randomised controlled trial, n = 34

    Symptoms improved about 51% with high-density ions, 54% with bright light and 17% with low-density ions. Small sample.

  5. Encouragingdetails to confirm

    Treatment of seasonal affective disorder with a high-output negative ionizer

    Terman M, Terman JS · Journal of Alternative and Complementary Medicine 1(1):87–92 · 1995

    Double-blind controlled trial, n = 25 (home use, 30 minutes each morning for 20 days)

    58% of people responded to high-density ions versus 15% with low-density ions. Symptoms returned in responders when treatment stopped, and no side effects were attributed to the treatment.

  6. Listeddetails to confirm

    A randomized, placebo-controlled trial of bright light and high-density negative air ions for treatment of seasonal affective disorder

    Flory R, Ametepe J, Bowers B · Psychiatry Research 177(1–2):101–8 · 2010

    Randomised trial in women with seasonal affective disorder (73 women recruited, per the 2013 meta-analysis)

    Compared bright light with high-density negative ions against a low-density placebo. A summary of its results is still to be added.

  7. Listeddetails to confirm

    Controlled trial evaluation of exposure duration to negative air ions for the treatment of seasonal affective disorder

    Bowers B, Flory R, Ametepe J, et al. · Psychiatry Research 259:7–14 · 2018

    Controlled trial of how long people are exposed

    Tested whether the length of daily exposure changes the effect. A summary of its results is still to be added.