title: Effects of electromagnetic radiation (bright light, extremely low-frequency magnetic fields, infrared radiation) on the circadian rhythm of melatonin synthesis, rectal temperature, and heart rate.
abstract: Electromagnetic spectra reduce melatonin production and delay the nadirs of rectal temperature and heart rate. Seven healthy men (16-22 yrs) completed 4 permuted sessions. The control session consisted of a 24-hours bedrest at < 30 lux, 18 degrees C, and < 50 dBA. In the experimental sessions, either light (1500 lux), magnetic field (16.7 Hz, 0.2 mT), or infrared radiation (65 degrees C) was applied from 5 pm to 1 am. Salivary melatonin level was determined hourly, rectal temperature and heart rate were continuously recorded. Melatonin synthesis was completely suppressed by light but resumed thereafter. The nadirs of rectal temperature and heart rate were delayed. The magnetic field had no effect. Infrared radiation elevated rectal temperature and heart rate. Only bright light affected the circadian rhythms of melatonin synthesis, rectal temperature, and heart rate, however, differently thus causing a dissociation, which might enhance the adverse effects of shiftwork in the long run.
authors.affiliation: Institute for Occupational Physiology, University of Dortmund, Ardeystr. 67, D-44139 Dortmund, Fed. Rep. Germany.
authors.forename: Barbara
authors.initials: B
authors.lastname: Griefahn
authors.forename: Christa
authors.initials: C
authors.lastname: Künemund
authors.forename: Meinolf
authors.initials: M
authors.lastname: Blaszkewicz
authors.forename: Alexander
authors.initials: A
authors.lastname: Lerchl
authors.forename: Gisela H
authors.initials: GH
authors.lastname: Degen
mesh_terms: D000293:Adolescent; D000328:Adult; D001831:Body Temperature / Q000528:radiation effects*; D002940:Circadian Rhythm / Q000528:radiation effects*; D004574:Electromagnetic Fields; D005858:Germany; D006339:Heart Rate / Q000528:radiation effects*; D006801:Humans; D007259:Infrared Rays; D008297:Male; D008550:Melatonin / Q000032:analysis / Q000096:biosynthesis* / Q000528:radiation effects; D012007:Rectum; D012016:Reference Values; D012463:Saliva / Q000737:chemistry
chemical_list: D008550:Melatonin