研究のタイプ: 医学/生物学の研究 (experimental study)

[睡眠時脳波の変化:パルス変調が異なる無線周波電磁界の影響] med./bio.

Sleep EEG alterations: effects of different pulse-modulated radio frequency electromagnetic fields.

掲載誌: J Sleep Res 2012; 21 (1): 50-58

【背景】これまでの研究で、睡眠時脳波パワースペクトル解析において、携帯電話無線周波電磁界RF EMF)へのばく露後、紡錘波周波数(約11-15 Hz)のパワー値の増加が観察されている。また、信号のパルス変調がこの影響の誘発に決定的に関与することも示唆されている。しかし、電磁界のどのような特定の要素が観察された変化の原因であるかは不明である。【目的】睡眠時紡錘波の範囲のパルス変調周波数成分がこのような影響の仲介に関与するか否かを調べること。【方法】被験者は30名の若い健康な男性。8時間睡眠の直前に30分間ばく露を行った。ばく露は3つの条件(900-MHz RF EMFの14Hzパルス変調波、同217Hzパルス変調波、擬似ばく露)で行い、各条件での睡眠実験の間隔は1週間とした。実際にばく露した2つの条件での比吸収率の空間ピーク値は2 W/ kgとした。ばく露が行われている間、被験者は3種類の認知タスク(注意反応時間作業記憶を測定するタスク:タスクの提示順は一定)を遂行した。【結果】14Hzパルス変調ばく露後において、ノンレム睡眠睡眠の第2段階)中に紡錘波の周波数範囲の脳波パワー値が増加した。217Hzパルス変調ばく露後においても、有意ではないが同様の増加が観察された。重要なことは、ばく露により誘発されたこの影響は、相当程度の個人間変動を示したことである。認知タスクの成績には、ばく露に関連した影響は見られなかった。【結論】影響の経時性には研究間でばらつきがあるものの、これまでの知見に一致して、今回の結果もパルス変調RF EMFが脳生理学的変化を起こす証拠を提示した。さらに言えば、生理学的な周波数の範囲の変調周波数成分にこのような影響を引き起こす能力があるかもしれないことを実験により示した。

The detailed summary of this article is not available in your language or incomplete. Would you like to see a complete translation of the summary? Then please contact us →

研究目的(著者による)

To study which electromagnetic field parameters may be responsible for previously reported results (see "related articles") on electrical brain activity during sleep. The authors hypothesized that pulse modulation components in the sleep spindle frequency range (e.g. 14 Hz) could act as potential mediators (the majority of previous studies found an influence of radiofrequency exposure in this frequency range). Additionally, pulse modulation at 217 Hz (component of the GSM signal) was studied.

詳細情報

Cognitive tasks were also included during exposure with the aim to elucidate previous inconclusive results regarding the effects of exposure to pulse modulated radiofrequency electromagnetic fields on cognition.
30 men participated. The protocol consisted of six study nights (three exposure nights at weekly intervals, each preceded by an adaptation night). Exposure lasted 30 min and ended 10 min before subjects had to go to bed.

影響評価項目

ばく露

ばく露 パラメータ
ばく露1: 900 MHz
Modulation type: pulsed
ばく露時間: continuous for 30 min.
pulse modulated at 14 Hz
  • SAR: 2 W/kg peak (10 g)
ばく露2: 900 MHz
Modulation type: pulsed
ばく露時間: continuous for 30 min.
pulse modulated at 217 Hz
  • SAR: 2 W/kg peak (10 g)

ばく露1

主たる特性
周波数 900 MHz
タイプ
  • electromagnetic field
ばく露時間 continuous for 30 min.
Additional information pulse modulated at 14 Hz
Modulation
Modulation type pulsed
Pulse width 2.3 ms
Repetition frequency 14 Hz
Pulse type rectangular
Additional information

crest factor = 30.95

ばく露装置
ばく露の発生源/構造
  • two planar antennas
Distance between exposed object and exposure source 115 mm
ばく露装置の詳細 subjects sat on a chair with their heads positioned between the antennas at a distance of 115 mm from the head with their centres 42 mm vertically above the ear canal; the left hemisphere of the brain was exposed
Sham exposure A sham exposure was conducted.
パラメータ
測定量 種別 Method Mass 備考
SAR 2 W/kg peak - 10 g -

ばく露2

主たる特性
周波数 900 MHz
タイプ
  • electromagnetic field
ばく露時間 continuous for 30 min.
Additional information pulse modulated at 217 Hz
Modulation
Modulation type pulsed
Pulse width 0.577 ms
Repetition frequency 217 Hz
Pulse type rectangular
Additional information

crest factor = 8

ばく露装置
ばく露の発生源/構造
  • E1と同じ装置
パラメータ
測定量 種別 Method Mass 備考
SAR 2 W/kg peak - 10 g -

Reference articles

  • Boutry CM et al. (2008): [ヒトボランティア研究に用いる各種のRFばく露装置のドシメトリ評価と比較]
  • Huber R et al. (2005): [局所的な大脳血流にパルス変調ラジオ周波数電磁界へのばく露は影響する]
  • Huber R et al. (2003): [ヒトでのラジオ周波電磁界ばく露:脳でのSAR分布の推定、睡眠と心拍への影響]
  • Huber R et al. (2000): [覚醒時のパルス状高周波電磁界へのばく露はヒトのEEGに影響する]

ばく露を受けた生物:

方法 影響評価項目/測定パラメータ/方法

研究対象とした生物試料:
研究対象とした臓器系:
調査の時期:
  • ばく露中
  • ばく露後

研究の主なアウトカム(著者による)

The data showed that pulse modulated radiofrequency electromagnetic fields altered the brain physiology. Specifically, 14 Hz pulse modulated exposure led to an increase in the EEG power spectrum during Non-REM sleep in the spindle frequency range (in the second Non-REM sleep episode, i.e. approx. 2-3 h after sleep onset). This suggests that the 14 Hz pulse modulation component, which is in the proximity to the physiological sleep spindle frequency, is one potential mediator of the observed effects on the sleep EEG. (A sleep spindle is a burst of oscillatory brain activity visible on an EEG that occurs during sleep stage 2. It consists of 12-14 Hz waves that occur for at least 0.5 seconds).
A similar but non-significant increase was also observed following the 217 Hz pulse modulated condition.
The exposure-induced effect showed a considerable individual variability (the majority of participants showed an increase, while some showed no change or even a decrease following the 14 Hz pulse modulated exposure).
There were no effects on sleep architecture, i.e. the responses seen in the EEG did not result in any changes of the sleep quality.
Some small effects on EEG spectral power during REM sleep were found, but there was no clear pattern.
Regarding cognitive performance, no clear exposure-related effects were found. Reaction speed tended to be slower with 217 Hz pulse modulation in all tasks, whereas accuracy of performance was largely unaffected.
In conclusion, the data provide further evidence for short-term effects of radiofrequency electromagnetic fields exposure on the sleep EEG in healthy, young male adults. In particular, pulse modulation frequency components within a physiological range were sufficient to induce these effects.

研究の種別:

研究助成

関連論文