Wednesday, April 27, 2016

Greater cell phone use may lower heart rate variability in healthy individuals which could increase risk for various health conditions

Greater cell phone use may lower heart rate variability in healthy individuals which could increase risk for various health conditions

Joel's comments: This study found that among healthy individuals 24 - 39 years of age greater use of cell phones was associated with lower heart rate variability (HRV).

HRV is the variation in the time interval between heartbeats. A low HRV indicates dominance of the sympathetic response. This is the fight or flight side of the autonomic system which is activated when the body experiences stress or inflammation. Lower HRV is associated with various health conditions including anxiety, depression, PTSD, metabolic syndrome, and coronary heart disease. In contrast, a high HRV indicates dominance of the parasympathetic response, the side of the autonomic system that promotes relaxation, digestion, sleep, and recovery.
The authors conclude that more research is needed to determine the clinical consequences of the lower HRV among heavier cell phone users.


The effects of the duration of mobile phone use on heart rate variability parameters in healthy subjects

Ekici B, Tanındı A, Ekici G, Diker E. The effects of the duration of mobile phone use on heart rate variability parameters in healthy subjects.Anatol J Cardiol. 2016 Apr 7. doi: 10.14744/AnatolJCardiol.2016.6717. [Epub ahead of print]


OBJECTIVE: This study aimed to estimate the influence of the duration of mobile phone use on heart rate variability (HRV) in healthy individuals.

METHODS: One hundred forty-eight individuals without any established systemic disease and who had undergone 24-h ambulatory ECG monitoring were included in the case-control study. All the individuals had been using mobile phones for more than 10 years. Three-channel 24-h Holter monitoring was performed to derive the mean heart rate, standard deviation of normal NN intervals (SDNN), standard deviation of 5-min (m) mean NN intervals (SDANN), the proportion of NN50 divided by the total number of NNs (pNN50), the root mean square differences of successive NN intervals (RMSSD), high (HF)-, low (LF)-, very low (VLF)-frequency power, total power components, and the LF/HF ratio. Individuals were divided into four groups according to their duration of mobile phone use [no mobile phone use (Control group), <30 1="" 2="" 30-60="" and="" day="" min="" roup="">60 min/day (Group 3)].

RESULTS: All the groups had similar features with regard to demographic and clinical characteristics. No significant arrhythmias were observed in any of the groups. The LF/HF ratio was higher, whereas the SDNN, SDANN, RMSSD, and pNN50 values were lower in the study groups than in the control group (p<0 .05="" among="" and="" differences="" groups="" heart="" identified="" no="" p="" power="" rate="" respect="" significant="" to="" total="" values="" vlf="" were="" with="">0.05).

CONCLUSION: In this study, it was shown that the duration of mobile phone use may affect the autonomic balance in healthy subjects. The electromagnetic field created by mobile phone use may induce HRV changes in the long term.

... In total, 103 patients were excluded because they met the exclusion criteria (n=77) or did not fulfill the inclusion criteria (n=26). Finally, 148 subjects (85 women and 63 men) with no established systemic disease were included in the study. All the participants (except the controls) had been using MPs [mobile phones] for >10 years prior to the study. The durations of mobile phone use were determined retrospectively from the individuals’ telephone billing records. Daily durations of mobile phone use were calculated automatically by dividing the total duration of calls (total min within a month) into the number of telephone calls (total number within a month) ....

The median age of the study population was 30.0 (24.0–39.0) years, and 42.6% of the participants were male ...

In our study, we found a negative correlation between the HRV parameters and the duration of mobile phone use. According to these findings, long-term MP use may reduce the HRV parameters and increase the sympathetic activity. In mobile phone use, the GSM transmits and receives microwave radiation
at a frequency of ≈900 and 1.800 MHz, respectively, and these frequencies excite the rotations of water molecules and some organic molecules and have been associated with thermal and non-thermal effects on the human body (10–13). The emission of these microwaves has been associated with the development
of symptoms such as headaches, a sensation of burning skin, fatigue, hot ears, extreme irritation, an increase in carelessness, forgetfulness, a decrease in reflexes, a clicking sound in the ears, and an increase in arterial blood pressure (10). However, despite these well-known effects of MPs, their long-term effect
on cardiac electrical activity has not been extensively studied and, to the best of our knowledge, whether MPs alter autonomic regulation of the cardiovascular system has not yet been extensively analyzed.

Generally, as MPs are held close to the head, this might affect the autonomic nervous system by their close brain heart connection, which modulates the cardiac pacemaker and provides beat-to-beat regulation of the cardiovascular rhythm (16)....

The novelty our work was to study the effects of long-term exposure to MPs on the cardiac electrical activity rather than studying the effects of MPs while talking. There was a negative association between the time domain HRV parameters, such as SDNN and SDANN, and the duration of MP use in our study. RMSSD and pNN50, which are supposed to be markers of parasympathetic activity, were also decreased in subjects using a MP for a long time. Although most of the other studies in the literature have reported changes in HRV that were compatible with increased parasympathetic activity during talking on the phone, we found that overall the long-term effects on HRV were in favor of an increased sympathovagal balance. Increased sympathetic activity and decreased parasympathetic tone could be detrimental and could contribute to a higher risk of affecting the cardiac electrical activity. The clinical long-term consequences should be further investigated.

In conclusion, the results of the present study demonstrate that a long-term duration of MP use may influence HRV and change the autonomic balance in favor of an increased sympathetic tone. An increase in the sympathetic tone concomitant with a decrease in the parasympathetic tone measured indirectly by analysis of HRV was observed in long-term MP users. EMF generated by the long-term use of MPs was the tentative explanation for the detrimental changes in HRV. Although in this study, no statistically significant difference was found between the groups, BMI differences can affect the results. So, this should also be taken into account in further studies. Large-scale prospective randomized clinical trials are needed to test the probable clinical consequences of HRV changes using different MP models.


Joel M. Moskowitz, Ph.D., Director
Center for Family and Community Health
School of Public Health
University of California, Berkeley

Electromagnetic Radiation Safety

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