8 healthysubjects took part in the study, which consisted of an experimental and a positive control part. The experimental part was comprised of a minimum of 60 trials. Each trial consisted of a 2 seconds exposure period and a subsequent 5 seconds non-exposure period. The last 2 seconds (seconds 4 and 5) of these 5 seconds were defined and recorded as the control period and the 2 seconds before (seconds 2 and 3) as the sham exposure period. A second set of identical trials was carried out as a positive control, where visible light was used as a stimulus during the 2 seconds exposure period.
pair of coaxial coils, each 130 cm in diameter and consisting of 250 turns of copper wire; the coils were 65 cm apart (the Helmholtz condition) by means of a wooden frame; the subjects sat on a comfortable plastic chair in a dark room with their eyes closed; their sagittal plane was perpendicular to the MF produced by the coils; MF was uniform within 5% in the region of the head and upper chest and within 20% over the thorax and pelvis