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Bioelectromagnetism

In view of Wever’s emphasis on the role of natural electric felds in entrainment of the normal circa­

dian rhythms, further information is needed on residual natural and artifcial felds in his test rooms.

Wever concluded that electromagnetic felds in the ELF range infuence human circadian rhythms.

However, replicable data are not shown.

In the past, it has been postulated that animal are sensitive to electric felds occurring in the atmo­

sphere and may obtain time cues from the daily variations. It also suggested that the electric feld may

be responsible for the 24 hours day-night rhythm.

Several results of the change of circadian rhythms of animals are summarized. Tese experiments

used 10 Hz electric felds with 10,000 times stronger than natural generating feld in the 8–14 Hz range.

Tis provided support for the concept that electric felds can afect circadian rhythms and act as a weak

Zeitgeber. Te efect of static electric felds on circadian rhythm of mice (Mus musculus) was investigated

(Dowse and Palmer, 1969). Te continuous locomotor activity of mice was recorded to determine the

efects of electric feld on circadian rhythm. Afer acclimatization to a light-dark cycle (200 fc, illumi­

nation, light period: 05:00–17:00 hours) for 10 days, electric felds were applied only in the light period

for 10–14 days, and then the light-dark cycle was reversed. Under dim light (1 fc), the mice were lef

with the electric feld applied for 25–35 days and then placed in constant light. Te results suggested a

possible efect of electric feld on locomotor activity rhythm. Mouse activity was entrained with on-of

cycle of the feld. It was proposed that the mouse detected electric feld extending into the cage because

of imperfect Faraday shielding and distortion by the feld wheel (Dowse and Palmer, 1969). However,

Roberts added a comment to this report (Roberts, 1969). When laboratory animals such as mice are

exposed to an atmospheric electric feld level of about 100 V/m, it is unreasonable to assume that there is

an efect considering the magnitude of the electric current in the animal body and the heat generated. It

is necessary to consider the efects of corona discharge, noise, etc. during the experiment, and fuctua­

tions in the electric feld due to positive and negative air inside the cage. Tis can hardly be regarded as

conclusive evidence for a static electric feld interaction. Te mice may have been responding to noise

generated by the electrical equipment, or to corona discharges from the cage which the mice could hear.

Te activity rhythms of Drosophila melanogaster were studied when a phase shif was added to the

24-hours cycle in an electric feld of 10 Hz, 0.15 kV/m (Dowse, 1982). Tis activity rhythm was examined

with the infrared beam blocked; a 6-hour phase shif in a 24-hour cycle disrupted the recorded activity

rhythms.

Shortened circadian rhythms were seen in the green fnches (Carduelis chloris L.) exposed to 10 Hz,

2.5 V/m electric feld (Wever, 1973). Te continuous feld exposure for 10–20 days sharply shortened the

circadian period from 24.8 to 23.9 hours. Nocturnal restlessness in the European brambling fnch asso­

ciated with seasonal migration was enhanced by a 10 Hz electric feld that illuminated certain perches

for which the birds exhibited a preference over unexposed perches in the same row. No diferences were

detected during the day (Wever, 1977).

As mentioned above, changes in free-running rhythms have been reported with exposure of 10 Hz,

2.5 V/m for human and fore green fnches (Carduelis chloris L.). Te feld gave a shortening of the spon­

taneous period, averaged 1.3 hours in human, and 0.8 hours in green fnches. Wever pointed that the

feld reduced internal desynchronization in humans and acted as a Zeitgeber. Tis experiment was

repeated with green fnches (Lintzen et al., 1989, 1992). Efects of the electric felds on activity of green

fnches (Carduelis chloris L.) and other experimental results have been reported (Lintzen et al., 1989).

Green fnches were exposed to an electric feld of 10 Hz, 2.5 V/m, and its efect on the free running

period was investigated. Te free running period was 23.66 ± 0.80 hours for the electric feld exposure

and 23.64 ± 0.77 hours for the control, which is opposite to the result pointed out by Wever, and no efect

of the electric feld exposure was observed. Tere was also no efect at 8.7 and 65.2 V/m. Te efect of

exposure of fruit fies to 10 Hz, 1 and 10 kV/m electric felds on circadian locomotor activity was reported

(Engelmann et al., 1996).

Recently, rat cardiac muscle cells were observed to be infuenced by weak magnetic feld (90 nT)

in 7.8 Hz (Elhalel et al., 2019). Te 3–4 days cultures are exposed to 7.8 Hz magnetic feld and three