Sleep after mobile phone exposure in subjects with mobile phone‐related symptoms

Several studies show increases in activity for certain frequency bands (10–14 Hz) and visually scored parameters during sleep after exposure to radiofrequency electromagnetic fields. A shortened REM latency has also been reported. We investigated the effects of a double‐blind radiofrequency exposure (884 MHz, GSM signaling standard including non‐DTX and DTX mode, time‐averaged 10 g psSAR of 1.4 W/kg) on self‐evaluated sleepiness and objective EEG measures during sleep. Forty‐eight subjects (mean age 28 years) underwent 3 h of controlled exposure (7:30–10:30 PM; active or sham) prior to sleep, followed by a full‐night polysomnographic recording in a sleep laboratory. The results demonstrated that following exposure, time in Stages 3 and 4 sleep (SWS, slow‐wave sleep) decreased by 9.5 min (12%) out of a total of 78.6 min, and time in Stage 2 sleep increased by 8.3 min (4%) out of a total of 196.3 min compared to sham. The latency to Stage 3 sleep was also prolonged by 4.8 min after exposure. Power density analysis indicated an enhanced activation in the frequency ranges 0.5–1.5 and 5.75–10.5 Hz during the first 30 min of Stage 2 sleep, with 7.5–11.75 Hz being elevated within the first hour of Stage 2 sleep, and bands 4.75–8.25 Hz elevated during the second hour of Stage 2 sleep. No pronounced power changes were observed in SWS or for the third hour of scored Stage 2 sleep. No differences were found between controls and subjects with prior complaints of mobile phone‐related symptoms. The results confirm previous findings that RF exposure increased the EEG alpha range in the sleep EEG, and indicated moderate impairment of SWS. Furthermore, reported differences in sensitivity to mobile phone use were not reflected in sleep parameters. Bioelectromagnetics 32:4–14, 2011. © 2010 Wiley‐Liss, Inc.     

大鼠慢波睡眠和睡眠过渡期脑电信号的小波变换分析

EEG信号经常包含许多快速的时变信息 ,将较长时间段的EEG信号近似看作平稳信号 ,进行FFT谱估计 ,存在其局限性。应用多分辨率小波变换方法 ,在频域和时域上可以同时定位分析大鼠慢波睡眠和睡眠过渡期脑电的动态变化特性。采用慢性埋植电极记录自由活动大鼠的皮层脑电 ,将信号用小波变换分解成δ、θ、α和 β四个分量 ,求各分量的功率和功率百分比的时间变化曲线 ,并与FFT功率谱分析结果进行比较。结果表明 :慢波睡眠期EEG中有 2 6 .2 %± 7.7%的时间段上δ分量功率小于总功率的 5 0 % ,且δ分量较大时 ,其他分量较小 ;δ分量较小时 ,其他分量较大 ,差别显著。此结果揭示了δ节律与θ和α节律之间的一种互补关系。而传统的FFT功率谱分析方法只能显示δ分量为主 (占总功率 70 .6 %± 6 .4 % )的功率谱 ,不能提供时变信息。对于睡眠过渡期的非稳态EEG信号 ,利用小波变换分解得到的θ和α分量可以鉴别出睡眠纺锤波 ,计算睡眠纺锤波的平均持续时间 ,并比较纺锤波和非纺锤波时期各个频谱分量的变化情况。由此可见 ,小波变换可用于计算新的EEG时频定量分析指标用于分析生理、病理和药理作用引起的睡眠EEG的变化过程 ,以弥补传统FFT功率谱分析的不足之处     

基于Flexible ICA的睡眠EEG及EOG中心电伪差的消除

提出了一种采用自适应非线性函数的ICA学习算法,Flexible ICA算法,并将其应用于睡眠EEG自动分期的前期预处理中,用于消除采集到的各通道信号中的心电伪差.实验结果证明,Flexible ICA算法能够快速有效的消除各通道的心电伪差,为后期的睡眠EEG自动分期打下了良好的基础.     

Real-Time Monitoring of Slow-Wave Sleep by Electroencephalogram Variance

Based on statistical variance as an index of electroencephalogram (EEG) parameters, we monitored slow-wave sleep in both humans and rats in real time and on-line with a widely used personal computer. This EEG variance method may be a useful tool to carry out biological rhythm research, including sleep studies.     

The contingency of parameters of human encephalograms and Schumann resonance electromagnetic fields revealed in monitoring studies

The contingency of variations in amplitude—frequency parameters of the main modes of extremely-low-frequency resonances of an ionospheric waveguide (Schumann resonances) and changes in human encephalograms in the frequency range of 6–16 Hz has been studied. The results obtained with the use of synchronized monitoring suggest that such contingency, expressed as indices of cross-correlation function, is statistically significant, varying from 0.12 to 0.65 at α = 0.95. It has been established that contingency is largely determined by the current level of solar and geomagnetic activity.     

Topographical EEG Mapping in a Case of Recurrent Sleep Terrors

Sleep terrors are characterized by marked CNS arousal and typically occur during stage 3-4 sleep within the first NREM cycle. Studies of the EEG during sleep terrors suggest that delta power and synchrony in the EEG may be important physiological markers of sleep terror presence and intensity. An EEG mapping study was undertaken with a single participant who experienced three sleep terror episodes in the laboratory. A one-minute section of EEG was sampled immediately prior to the onset of each of the three sleep terrors. Similar EEG sections were taken from 10 healthy sex- and age-matched controls. The sleep tenors and control (normative) data were then compared topographically with z-scores (z-mapping). The z-maps indicated that all three sleep terrors contained more total and delta power in central and frontal areas than the control EEG sections. Moreover, relative delta power in these areas for the three sleep terrors was proportional to the subjective intensity of the episode. Although this pre-arousal EEG pattern may be related to ongoing slow-wave sleep mentation that may sometimes trigger sleep terror episodes, its functional significance remains an open question. The results demonstrate the utility of EEG mapping for the quantification of brain activation during sleep terror attacks and suggest that discrete activity profiles are identifiable for different types of dreaming-related arousal.     

Individual differences in the effects of mobile phone exposure on human sleep: rethinking the problem

Mobile phone exposure‐related effects on the human electroencephalogram (EEG) have been shown during both waking and sleep states, albeit with slight differences in the frequency affected. This discrepancy, combined with studies that failed to find effects, has led many to conclude that no consistent effects exist. We hypothesised that these differences might partly be due to individual variability in response, and that mobile phone emissions may in fact have large but differential effects on human brain activity. Twenty volunteers from our previous study underwent an adaptation night followed by two experimental nights in which they were randomly exposed to two conditions (Active and Sham), followed by a full‐night sleep episode. The EEG spectral power was increased in the sleep spindle frequency range in the first 30 min of non‐rapid eye movement (non‐REM) sleep following Active exposure. This increase was more prominent in the participants that showed an increase in the original study. These results confirm previous findings of mobile phone‐like emissions affecting the EEG during non‐REM sleep. Importantly, this low‐level effect was also shown to be sensitive to individual variability. Furthermore, this indicates that previous negative results are not strong evidence for a lack of an effect and, given the far‐reaching implications of mobile phone research, we may need to rethink the interpretation of results and the manner in which research is conducted in this field. Bioelectromagnetics 33:86–93, 2012. © 2011 Wiley Periodicals, Inc.     

Dim Light at Night Does Not Disrupt Timing or Quality of Sleep in Mice

Artificial nighttime illumination has recently become commonplace throughout the world; however, in common with other animals, humans have not evolved in the ecological context of chronic light at night. With prevailing evidence linking the circadian, endocrine, immune, and metabolic systems, understanding these relationships is important to understanding the etiology and progression of several diseases. To eliminate the covariate of sleep disruption in light at night studies, researchers often use nocturnal animals. However, the assumption that light at night does not affect sleep in nocturnal animals remains unspecified. To test the effects of light at night on sleep, we maintained Swiss-Webster mice in standard light/dark (LD) or dim light at night (DLAN) conditions for 8–10 wks and then measured electroencephalogram (EEG) and electromyogram (EMG) biopotentials via wireless telemetry over the course of two consecutive days to determine differences in sleep timing and homeostasis. Results show no statistical differences in total percent time, number of episodes, maximum or average episode durations in wake, slow-wave sleep (SWS), or rapid eye movement (REM) sleep. No differences were evident in SWS delta power, an index of sleep drive, between groups. Mice kept in DLAN conditions showed a relative increase in REM sleep during the first few hours after the dark/light transition. Both groups displayed normal 24-h circadian rhythms as measured by voluntary running wheel activity. Groups did not differ in body mass, but a marked negative correlation of body mass with percent time spent awake and a positive correlation of body mass with time spent in SWS was evident. Elevated body mass was also associated with shorter maximum wake episode durations, indicating heavier animals had more trouble remaining in the wake vigilance state for extended periods of time. Body mass did not correlate with activity levels, nor did activity levels correlate with time spent in different sleep states. These data indicate that heavier animals tend to sleep more, potentially contributing to further weight gain. We conclude that chronic DLAN exposure does not significantly affect sleep timing or homeostasis in mice, supporting the use of dim light with nocturnal rodents in chronobiology research to eliminate the possible covariate of sleep disruption.     

The impact of extremely low frequency electromagnetic fields on stream periphyton: an eleven-year study

Potential effects of extremely low frequency (ELF) electromagnetic fields on periphyton were studied from 1983 to 1993 using a Before, After, Control and Impact design. The study was conducted at two sites on the Ford River, a fourth-order brown water trout stream in Dickinson County, Michigan. The Reference site received 4.9–6.5 times less exposure to ground electric fields and from 300 to 334 times less exposure to magnetic flux from 1989 to 1993 when the antenna was operational at 76 Hz than did the Antenna site. The objective of the study was to determine if ELF electromagnetic fields had caused changes in structure and/or function of algal communities in the Ford River. Significant differences in chlorophyll a standing crop and daily accumulation rate (a surrogate for primary productivity), and organic matter standing crop and daily accumulation rate were observed between the Reference and Antenna site after the antenna became operational. These four related community function variables all increased at the Antenna site with largest and most consistent increases occurring for chlorophyll measures. Compared to pre-operational data, the increase in chlorophyll at the Antenna site also occurred during a period of low amperage testing in 1986–1988, and did not increase further when the antenna became fully operational in 1989, indicating a low threshold for response. There was no significant differences between the Antenna and Reference sites in community structure variables such as diversity, evenness and the relative abundance of dominant diatoms. Thus, 76 Hz ELF electromagnetic radiation apparently did not change the basic makeup of the diatom community but did increase accumulation rates and standing crops of chlorophyll a and organic matter.     

Do people with idiopathic environmental intolerance attributed to electromagnetic fields display physiological effects when exposed to electromagnetic fields? A systematic review of provocation studies

Idiopathic environmental intolerance attributed to electromagnetic fields (IEI‐EMF) is a controversial illness in which people report symptoms that they believe are triggered by exposure to EMF. Double‐blind experiments have found no association between the presence of EMF and self‐reported outcomes in people with IEI‐EMF. No systematic review has assessed whether EMF exposure triggers physiological or cognitive changes in this group. Using a systematic literature search, we identified 29 single or double‐blind experiments in which participants with IEI‐EMF were exposed to different EMF levels and in which objectively measured outcomes were assessed. Five studies identified significant effects of exposure such as reduced heart rate and blood pressure, altered pupillary light reflex, reduced visual attention and perception, improved spatial memory, movement away from an EMF source during sleep and altered EEG during sleep. In most cases, these were isolated results that other studies failed to replicate. For the sleep EEG findings, the results reflected similar changes in the IEI‐EMF participants and a non‐IEI‐EMF control group. At present, there is no reliable evidence to suggest that people with IEI‐EMF experience unusual physiological reactions as a result of exposure to EMF. This supports suggestions that EMF is not the main cause of their ill health. Bioelectromagnetics. Bioelectromagnetics 32:593–609, 2011. © 2011 Wiley Periodicals, Inc.     

The sleep-enhancing effect of valerian inhalation and sleep-shortening effect of lemon inhalation

We examined the effects of odorant inhalation on the sleep-wake states in rats. Odorants used in the experiment were clove, jasmine, lavender, lemon, peppermint, pine, rose, sandalwood, valerian, and ylang-ylang. Valerian and rose inhalation significantly prolonged the pentobarbital-induced sleeping time, whereas lemon inhalation significantly shortened it. The effect of valerian inhalation was markedly noticeable. In the anosmic rats, a significant effect of odorants on the pentobarbital sleep time was not seen. Electroencephalographic studies on natural sleep revealed that rose inhalation did not exert any significant effect on sleep, but a significant shortening in sleep latency and a significant prolonging in total sleep time were observed with valerian inhalation, whereas a significant prolonging in sleep latency was observed with lemon inhalation. Such effects of valerian and lemon inhalation were not admitted in anosmic rats. gamma-Aminobutyric acid (GABA) transaminase assay indicates that valerian inhalation decreases the activity of the enzyme and enhances GABA activity. Although valerian has been reported to exert a good effect for sleep as a medicine for internal use, the present study is the first medical report suggesting that the inhalation of valerian may enhance the sleep. On the other hand, the present results may suggest the possibility that lemon inhalation may cause a worsening of insomnia symptoms.     

睡眠研究的科学前沿

关于睡眠机制的研究是一门历史悠久的学科.在过去的几十年中,运用细胞电生理学来研究睡眠取得了可喜的成果.由于种种技术上的困难,近年来该领域的研究多集中于临床和医学范围,例如嗜睡症、抑郁症等.虽说睡眠的节律性较易理解,但作为其本质———睡眠的基因和分子水平的自动平衡调节仍是一个谜.细胞因子(IL-1和TNFα)对睡眠的诱导作用已显示从分子水平上了解睡眠的可能性.到目前为止,关于睡眠的功能已有不少理论和假说,但人类对睡眠的生化机制的认识尚处于起步阶段.     

The effect of chronic exposure to extremely low-frequency electromagnetic fields on sleep quality,stress, depression and anxiety

Exposure to extremely low-frequency electromagnetic fields (ELF-EMF) is inevitable in some industries. There are concerns about the possible effects of this exposure. The present study aimed to investigate the effect of chronic exposure to extremely low-frequency electromagnetic fields on sleep quality, stress, depression and anxiety among power plant workers.

In this cross-sectional study, 132 power plant workers were included as the exposed group and 143 other workers were included as the unexposed group. The intensity of ELF-EMF at work stations was measured by using the IEEE Std C95.3.1 standard and then the time weighted average was calculated. Sleep quality, stress, depression and anxiety were measured by using the Pittsburgh Sleep Quality Index Questionnaire; and the Depression, Anxiety and Stress Scale.

The workers in the exposed group experienced significantly poorer sleep quality than the unexposed group. Depression was also more severe in the exposed group than the unexposed group (P = 0.039). Increased exposure to ELF-EMF had a direct and significant relation with increased stress, depression, and anxiety. Sleep quality in technicians with the highest exposure was significantly lower than the other groups.

This study suggests that long-term occupational exposure to ELF-EMF may lead to depression, stress, anxiety and poor sleep quality.     

No effects of a single 3G UMTS mobile phone exposure on spontaneous EEG activity,ERP correlates,and automatic deviance detection

Potential effects of a 30 min exposure to third generation (3G) Universal Mobile Telecommunications System (UMTS) mobile phone‐like electromagnetic fields (EMFs) were investigated on human brain electrical activity in two experiments. In the first experiment, spontaneous electroencephalography (sEEG) was analyzed (n = 17); in the second experiment, auditory event‐related potentials (ERPs) and automatic deviance detection processes reflected by mismatch negativity (MMN) were investigated in a passive oddball paradigm (n = 26). Both sEEG and ERP experiments followed a double‐blind protocol where subjects were exposed to either genuine or sham irradiation in two separate sessions. In both experiments, electroencephalograms (EEG) were recorded at midline electrode sites before and after exposure while subjects were watching a silent documentary. Spectral power of sEEG data was analyzed in the delta, theta, alpha, and beta frequency bands. In the ERP experiment, subjects were presented with a random series of standard (90%) and frequency‐deviant (10%) tones in a passive binaural oddball paradigm. The amplitude and latency of the P50, N100, P200, MMN, and P3a components were analyzed. We found no measurable effects of a 30 min 3G mobile phone irradiation on the EEG spectral power in any frequency band studied. Also, we found no significant effects of EMF irradiation on the amplitude and latency of any of the ERP components. In summary, the present results do not support the notion that a 30 min unilateral 3G EMF exposure interferes with human sEEG activity, auditory evoked potentials or automatic deviance detection indexed by MMN. Bioelectromagnetics 34:31–42, 2013. © 2012 Wiley Periodicals, Inc.