The effect of bright light exposure on pupillary fluctuations in healthy subjects.
BACKGROUND
Light therapy is thought to be the first choice treatment of winter depression. However, its way of action is poorly understood. In order to find a solid effect of bright artificial light, we studied its possible alerting action through the spontaneous fluctuations of the pupil, considered to be an objective measurement of vigilance.


METHODS
Pupillary fluctuations of 10 healthy subjects (mean age: 22+/-1 S.D. years) were measured for 60 s before and 15 min after 0.5 h, 10000-lux light exposure. The cumulative change in pupil size, characterised by the pupillary unrest index (PUI) decreased at each subject, and this decrease was in average 35+/-4.4% S.E.M. The average pupillary diameters were unchanged (101+/-2.2% S.E.M.). This analysis revealed that the slow components of the pupillary fluctuations also decreased considerably.


CONCLUSIONS
There was no dim light or other placebo control of the light treatment.


CONCLUSIONS
Bright light exposure significantly influenced the pupillary fluctuations. We suppose that bright light exposure increases the level of alertness, and this could be a possible way by which bright artificial light exerts a beneficial effect also in affective disorders.
Szabó
Zoltán
Z
Department of Psychiatry, Albert Szent-Györgyi Center for Medical and Pharmaceutical Sciences, Faculty of Medicine, University of Szeged, Semmelweis u.6, Szeged H-6725, Hungary. szaboz@nepsy.szote.u-szeged.hu
Tokaji
Zsolt
Z
Kálmán
János
J
Oroszi
László
L
Pestenácz
Anikó
A
Janka
Zoltán
Z
D000328:Adult; D005260:Female; D006304:Health Status; D006801:Humans; D008027:Light; D008297:Male; D011680:Pupil / Q000502:physiology*