Study type: Medical/biological study (experimental study)

Effect of a nighttime magnetic field exposure on sleep patterns in young women. med./bio.

Published in: Am J Epidemiol 2004; 160 (3): 224-229

Aim of study (acc. to author)

To determine the effect of a continuous, 60 Hz, nighttime magnetic field exposure on sleep outcomes in young women sleeping at home.

Background/further details

Women were studied during two 5-night measurement periods: 1) exposure (0.41-1.21 µT); 2) sham exposure (ambient magnetic field levels, 0.001-0.50 µT). 19 subjects completed one measurement period and 58 completed both. Subjects were between 20-40 years of age, had regular mentrual cycles, were not taking oral contraceptives, and had not breastfed or been pregnant during the previous year. Both measurement periods started two days after the luteinizing hormone surge of the menstrual cycle.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 60 Hz
Exposure duration: continuous for 5 nights

Exposure 1

Main characteristics
Frequency 60 Hz
Type
Waveform
Exposure duration continuous for 5 nights
Exposure setup
Exposure source
  • electric tooth brush charger underneath the bed
Setup exposure directed at the center of the pillow
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 0.001 µT minimum measured - 0.001 µT - 0.5 µT; ambient feld
magnetic flux density 0.5 µT maximum measured - ambient field
magnetic flux density 0.41 µT minimum measured - 0.41 µT - 1.21 µT exposure field
magnetic flux density 1.21 µT maximum measured - exposure field

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • during exposure

Main outcome of study (acc. to author)

During the sham exposure (ambient magnetic field) subjects slept on average 6 hours and 58 minutes, with a sleep efficiency of 88.3 %. During the exposure period they slept on average 7 hours and 1 minute, with a sleep efficiacy of 88.4 %. Sleep outcomes were not significantly different between the exposure and sham exposure.

Study character:

Study funded by

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