'Natural' light treatment of seasonal affective disorder

J Affect Disord. 1996 Apr 12;37(2-3):109-20. doi: 10.1016/0165-0327(95)00081-x.


Patients with seasonal affective disorder (SAD) were treated for 1 week either with a daily 1-h morning walk outdoors (natural light) or low-dose artificial light (0.5 h@2800 lux). The latter treatment (given under double-blind conditions) can be considered mainly placebo and did not improve any of the depression self-ratings, whereas natural light exposure improved all self-ratings. According to the Hamilton depression score, 25% remitted after low-dose artificial light and 50% after the walk. Sleep duration or timing were not crucial for the therapeutic response. The morning walk phase-advanced the onset and/or offset of salivary melatonin secretion, but individual clinical improvement could not be correlated with specific phase-shifts. Morning cortisol was decreased. Low-dose artificial light did not modify melatonin or cortisol patterns. This is the first study to provide evidence for the use of outdoor light exposure as a potential alternative or adjuvant to conventional artificial light therapy in SAD.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adult
  • Circadian Rhythm / physiology
  • Double-Blind Method
  • Female
  • Humans
  • Hydrocortisone / metabolism
  • Male
  • Melatonin / metabolism
  • Middle Aged
  • Personality Inventory
  • Phototherapy / methods*
  • Saliva / metabolism
  • Seasonal Affective Disorder / diagnosis
  • Seasonal Affective Disorder / physiopathology
  • Seasonal Affective Disorder / psychology
  • Seasonal Affective Disorder / therapy*
  • Sleep Stages / physiology
  • Sunlight*
  • Treatment Outcome
  • Walking* / psychology


  • Melatonin
  • Hydrocortisone