Effects of cell phone radio-frequency radiation on the

Chronic Diseases Prevention Review 13 (2020) 9-21

Copyright@2020 by Chronic Diseases Prevention Review

9

Available at http:// www.cancercellresearch.org ISSN 2158-0820

Effects of cell phone radio-frequency radiation on the sleep outcomes: A systematic review and Meta-Analysis of randomized controlled trials Han Zhou1, Rui Xu1, Kunxing Ding1, Cuiping Liu2, Feng Zhong1, * 1School of Public Health, Qingdao University, Qingdao, 266021, China

2School of Nursing, Qingdao University, Qingdao, 266021, China

Abstract: Sleep disorders have become an important public health issue affecting people's physical health. In recent years, the impact of mobile phone radio-frequency (RF) radiation on the outcome of sleep caused the attention of scholars. We systematically searched EMBASE, Web of Science, Cochrane Library and PubMed until November 2018. All articles on the relationship between radiofrequency radiation and sleep results from polysomnography were included. These articles were randomized controlled trials (RCT) in English only. The aim was to investigate the effects of radio frequency (RF) radiation from mobile phones on sleep outcomes. 17 RCTs, including 398 participants, met the criteria for a meta-analysis. The results showed that exposure to mobile phone radio frequency radiation had no effect on sleep staging indicators and sleep quality indicators. However, results of subgroup analysis according to the exposure frequency, publication years, and exposure time demonstrated that exposure to non-217Hz RF radiation could increase arousal-index per hour (standardized mean difference = 1.22, 95% confidence interval [0.68, 1.76]; p < 0.001). The articles published before 2000 showed that total sleep time (mean difference = 4.80, 95% confidence interval=[3.70, 5.90]; p < 0.001) had increased, while articles published after 2001 showed that total sleep time (mean difference = -2.56, 95% confidence interval= [-4.25, -0.87]; p = 0.003) had decreased. RF exposure before sleep could increase the time of stage 1 (mean difference = 0.91, 95% confidence interval= [0.32, 1.50]; p = 0.003). Therefore, short-term exposure to cell phone RF radiation had no impacts on people's overall sleep outcomes.

Keywords: Cell phone; RF radiation; Sleep; Meta-analysis

Received 26 December 2019, Revised 23 January 2020, Accepted 30 January 2020

*Corresponding Author: Feng Zhong, [email protected]

1. Introduction

According to the World Health Organization

(WHO), 27% of people worldwide has sleep

disorders, which has become a major public health

problem in the world. Many people suffered from

sleep disorders such as insufficient sleep and daytime

sleepiness, etc. [1, 2] Fernando AT et al. found that

37.2% subjects were suffering from sleep-phase

disorders in New Zealand[3]. Falavigna A et al.

found that 60 percent of people were reported

sleeping problems in Southern Brazil[4]. Decreased

sleep quality in adults could lead to short- and long-

term detrimental health outcomes, including an

increase in daily stress, impaired memory, emotional

abnormalities, reduced athletic ability, reduced

immunity, stunted growth, accelerated aging, and

substance abuse, etc.[5-10] Therefore, good sleep

quality be beneficial to prevent a range of disorders

and keep health.

Sleep problems can be caused by several factors

including disease status, dietary factors, mental

health, and lifestyle. The number of people using

mobile phones is growing year by year [11]. More

and more scholars believed that radio-frequency (RF)

radiation from cell phones can be an important factor

affecting the quality of sleep. The potential health

effects of mobile phone (MP) electromagnetic field

(EMF) exposure has been identified by WHO as a

high priority research area, and the health effects of

prolonged exposure to RF radiation needed to be

studied further[12]. Whether the use of cell phones

could result in prolonged sleep latency and

subsequent side effects remains unclear[13]. Several

studies has found that RF radiation of a cell phone

can cause sleep disorders by changing rapid-eye

movement (REM) sleep[14, 15]. Some believed that

exposure to RF radiation in cell phones could shorten

slow wave sleep (SWS) time[16, 17] or extend the

REM sleep latency[18], while others argued that RF

radiation has no effects on sleep outcomes[19-23].

To sum up, the effects of cell phone RF radiation

on sleep outcomes remains controversial and there be

no evidence of the overall effects' evaluation.

Therefore, we performed meta-analysis and

systematic review to explore the impacts of mobile

phone RF radiation on sleep outcomes.

2. Method

2.1. Types of participants

All subjects were non-smokers and reported to be

healthy and had no sleep problems. Elimination of

personal or family psychopathology, chronic illness,

sleep disorders, and current history of the use of

psychotropic or other medications. During the study



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period, alcohol was banned and the subject was

informed in detail of the study's intentions and

obtained written consent.

2.2. Types of studies and interventions

Randomized controlled double-blind crossover

design experiment. The control group was sham

group, and the experimental group was radio

frequency radiation (cell phone or analog cell phone

signal) exposure group.

2.3. Search strategy

This search strategy was developed in order to

identify studies which explored the association

between exposure to cell phone RF and sleep

outcomes. This review was conducted using

PRISMA-P guidelines[24]. We conducted MeSH and

keywords search using terms such as RF, sleep, and

cell phone, etc. Search queries were performed on

the electronic databases PubMed, EMBASE, Web of

Science and the Cochrane Library. The entire search

process was completed on November 17th, 2018.

PubMed was searched using the following

terminology: ((‘cell phone’ OR ‘mobile phone’ OR

‘cellular phone’ OR ‘smart phone’ OR ‘electronic

media’ OR ‘cell phone’ [MeSH Terms] OR ‘mobile

equipment’ OR ‘mobile communication’ OR

‘handset’ OR ‘mobile telephone’) AND (‘RF’ OR

‘radio frequency’ OR ‘radiation’ OR ‘RF energy’)

AND (‘sleep’ OR ‘sleep’ [MeSH Terms]) AND

(‘randomized controlled trial’ [Publication Type] OR

‘random’ OR ‘controlled’ OR ‘trial’)). The other

databases were searched using similar terminologies.

Specific search strategies were detailed in

supplement Figure 1.

Figure 1. PRISMA Flowchart of the Searched, Identified, and Included Studies.

2.4. Inclusion and exclusion criteria Included studies met the following criteria: (a)

original double-blinded randomized controlled trials;



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(b) RF radiation signals generated strictly from cell

phones; (c) outcomes including sleep staging and

sleep quality experimented by polysomnography

analyzer; (d) complete data records and (e) the study

was published in English as a full-text article in

journal. Excluded studies if (a) Animal experiments,

(b) Non-English papers, (c) Reviews, letters or

comments and (d) Incomplete data. The development

of the standard was independently evaluated by two

researchers (Han Zhou and Feng Zhong).

2.5. Data extraction and management

The full texts of all relevant articles were retrieved

and assessed for eligibility. Two reviewers

independently extracted the data, and a third

reviewer was responsible for resolving the

differences. Relevant data included first author's

surname, year of publication, participant's country of

origin, age, gender, the sample size of control and

experimental groups, sleep outcomes, signal type and

experimental stage. We conducted quality

assessments and publication bias evaluations for all

of the articles included[25]. For details, see Figure 1

and Figure 2.

Figure 2. Risk of bias graph.

2.6. Definition of indexes

Our data were all continuous variables based on

the polysomnography analyzer. Polysomnography

recorded electroencephalogram (EEG),

electrocardiogram, electromyography, and

electrooculogram to determine sleep status and sleep

parameters. Exposure to RF radiation prior to

nighttime sleep was classified as "RF exposure

before sleep". No intermittent exposures throughout

the night and discontinuous RF sequence exposure

were classified as "RF exposure all night." The

number of awakenings or awakening time during

sleep was defined as "waking in the sleep". Short-

term exposure to mobile phone RF radiation was

defined as a contact time of 10 days (determined

based on the experimental time included in the

literature). Sleep outcomes consisted of sleep staging

indexes and sleep quality indexes. The sleep staging

indexes included REM sleep, SWS, stage 1, stage 2,

total sleep time (TST), sleep period time (SPT). The

sleep quality indexes included sleep latency, REM

sleep latency, waking during sleep, movement time,

arousal index (per hour).

2.7. Assessment of risk of bias

Review Manager 5.3 was used to assess the risk in

our study. Authors Han Zhou, Feng Zhong, Rui Xu

and Kunxiang Ding independently assessed the risk

in all domains including random number generation,

allocation concealment, blinding of intervention and

outcome assessors, completeness of follow-up,

selectivity of reporting and other potential sources of

bias. The risk was assessed as low, high or unclear

risk based on the Cochrane Collaboration guidelines.

2.8. Statistical analysis

We used Review Manager 5.3 for the following

statistical analysis. The quality assessment tool

contained seven questions about the quality

assessment of the paper. Two independent reviewers

assessed risk of bias using the Cochrane

Collaboration's Risk of Bias Tool for RCT. The

following individual domains were assessed by two

investigators as either low, unclear, or high risk of

bias. The research data contained continuous

variables in the form of Mean ± SD. We used

standardized mean difference (SMD) for the

calculation when the measurement units were

inconsistent and Weighted Mean Difference (WMD)

if the units of measure were consistent. The Cochran

Q test and I2 values were used to determine the

heterogeneity of the study. The model was based on



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the size of I2. Considering the existence of

heterogeneity, when I2 > 50%, a random effects

model was used, and a fixed effects model was used

when I2 ≤ 50%. We performed a subgroup analysis

of the study of I2 > 25%[26]. After comparisons with

significant heterogeneity, we made a sensitivity

analysis in which one study was removed to identify

the possible source of heterogeneity; the study that

resulted in the greatest decrease in heterogeneity was

excluded. Subgroup analyses were also performed to

check for possible sources of heterogeneity

attributable to the study characteristics. Review

manager 5.3 was used for sensitivity, heterogeneity

analyses, quality assessment and publication bias.

3. Results

3.1. Characteristics of Studies

A PRISMA flow diagram of the search results was

seen in Figure 1. 17 experiments were included in

this meta-analysis. Overall, studies in the meta-

analysis included Germans (n = 6); Swiss (n = 7);

Swedes (n = 1); Japanese (n = 1); and Australians (n

= 2). The subjects in nine trials were exposed to RF

radiation before going to sleep, and the others were

exposed all night. A comparison of the included

study characteristics was detailed in Table 1. All

records of sleep outcomes were based on

polysomnography.

3.2. Risk of bias in included studies

The small sample size (< 20 people) was classified

as high risk17. Both blinding of outcome assessment

not mentioned and the subjects only including males

were considered to unclear risk. The risk of bias

assessment for each included study was shown in

Figure 2 and Figure 3. All RCTs had a low risk of

bias for random sequence generation, allocation

concealment, incomplete data reporting and blinding

of participants and personnel. Blinding of outcomes

assessment among all the articles were unclear risk

of bias because they were not mentioned in the

articles. Seven studies (7 [41.2%]) had a high risk of

bias for selective reporting. The other bias was

unclear risk (12 [71.0%]) in 12 studies in which the

subjects were only males.

3.3. Effects of RF radiation from cell phones on

sleep staging indexes

Exposure to RF radiation shortened the SPT (MD,

-2.28 [-3.29, -1.26]; P < 0.001). But, the results of the

sensitivity analysis showed that the change of SPT

was completely caused by one of the articles, this

positive result was excluded. So, compared with the

control groups, there was no statistical significance

on the influences of cell phone RF radiation on sleep

staging indexes (REM sleep, SWS, stage 1, stage 2,

TST, SPT) in the RF radiation group, which was

shown in the Figure 5.

Figure 3. Risk of bias summary.



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Figure 4. Sleep quality indexes with RF radiation. Effect of cell phone RF (radio-frequency)

radiation on people sleep quality indexes [Sleep latency; REM (rapid-eye-movement) sleep latency;

Waking in the sleep; Movement time; Arousal index (per hour); Sleep efficiency].



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Figure 5. Sleep staging indexes with RF radiation. Effect of cell phone RF (radio-frequency)

radiation on people Sleep staging indexes [REM (rapid-eye-movement) sleep; SWS (slow wave

sleep); Stage 1; Stage 2; TST (total sleep time); SPT (sleep period time)].



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Table 1. Characteristics of included studies

First

author and

year

Type of

study Blind Country Age range N n/Gender

Exposure

time

sleeping

time Signal type

Sleep

Outcomes

Experimental

stage

Borbe'ly,

AA. 199927 RCT

Double

blind Switzerland 27.3±4.2

24

(24-24) 24 males All night 23:00-7:00

GSM 900 MHz 1736Hz (2, 8, 217,

1736 Hz)

base station-like signal

(1)(2)(4)(5)(8

)(9)

4d*

Two stages

Interval 1 week

Danker-

Hopfe, H.

201114

RCT Double

blind Germany 25.3 ±2.6

30

(30-30) 30 males All night 23:00-7:00

GSM 900 217Hz (217 Hz),

Hand-set like signal

WCDMA/UMTS

(1966 MHz)

(1)(2)(3)(4)(5

)(7)(8)(9)(10)

(11)

10d*

Interval 1 week

Fritzer, G.

200738 RCT

Double

blind Germany 28.3±4.1

20

(10-10) 20 males All night

10:00/12:00-

6:45

GSM 900

(2, 8, 217 Hz and 1736 Hz)

handset-like signal

(1)(2)(3)(4)(5

)(6)(7)(8)(9)(

10)(12)

8d*

One stages

Hinrichs, H.

200539 RCT

Double

blind Germany 20-28

13

(13-13)

12 females

1 males All night 23:00-7:00

GSM 1800

(Far-field characteristic, 1736 Hz

pulse

frequency)

Base station like signal

(1)(2)(3)(4)(6

)(7)(8)(9)(10)

(11)

5d*

One stages

Huber, R.

200040 RCT

Double

blind Switzerland 20-25

16

(16-16) 16 males All night 23:00-7:00

GSM 900

1736Hz (2, 8, 217, 1736 Hz)


(1)(2)(3)(4)(5

)(6)(8)(9)(10)

6d*

Three stages

Interval 1 week

Huber, R.

200233 RCT

Double

blind Switzerland 20-25

16

(16-16) 16 males Before sleep 23:00-7:00

GSM900

2,8,217,1736 Hz

(Non-modulated continuous wave

and

pulse-modulated

signal)

Handset-like signal

(1)(2)(3)(4)(5

)(6)(9)(10)

4d*

Two stages

Interval 1 week

Loughran,

SP. 200528 RCT

Double

blind Australia 27.9 ± 7.9

50

(50-50)

23 females

27 males Before sleep 22:30-6:00

GSM900

217 Hz

Handset-like signal

(1)(2)(3)(5)(7

)(8)(9)(10)(1

2)

4d*

Two stages

Interval 1 week

Loughran,

SP. 201223 RCT

Double

blind Australia 27.9 ± 6.5

20

(20-20)

13 females


GSM 894,6

217 Hz

Handset-like signal

(1)(3)(7)(10)(

12)

3d*

One stages

Lowden, A.

201116 RCT

Double

blind Sweden 18-44

48

(48-48)

27 females


GSM，884 MHz/1736Hz (2,8,217

Hz and

1736 Hz)

Handset-like signal

(2)(4)(7)(8)(9

)(10)(11)(12)

2d*

Two stages

Interval 1 week



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Data presented as mean ± standard deviation. RCT, Randomized Controlled Trial; N, sample size; GSM, Global System for Mobile communication.

Note：(1) sleep latency (2) REM sleep (3) REM sleep latency (4) waking in the sleep (5) slow-wave sleep (6) movement time (7) sleep efficiency (8) stage 1 (9) stage 2 (10)

TST (11) SPT (12) Arousal index (per hour)

*The actual time of the experiment

Lustenb

erger, C.

201521

RCT Double

blind Switzerland 23.3 ± 0.5

19

(19-19) 19 males Before sleep

10:50-

6:50/11:40-

7:40

RF 900 MHz

(Modulation 2 Hz,

8 Hz and harmonics

o20 Hz)

(1)(2)(3)(4)

4d*

Two stages

Interval 1 week

Mann,

K.

199641

RCT Double

blind Germany 27.3 ± 4.2

12

(12-12) 12 males All night 23:00-7:00

GSM 900

217 Hz

Handset-like signal

(1)(2)(3)(4)(5

)(7)(8)(9)(10)

(11)

3d*

One stages

Nakatan

i-

Enomot

o, S.

201342

RCT Double

blind Japan 30.6 ± 6.1

19

(19-19)

7 females

12 males All night 23:00-7:00 WCDMA 1950 MHz

(1)(2)(3)(4)(5

)(7)(12)

3d*

One stages

Regel,

SJ.

200717

RCT Double


15

(15-15) 15 males Before sleep 23:00-7:00

GSM 900 MHz

1736Hz (2, 8, 217, 1736 Hz)


(1)(2)(3)(4)(5

)(6)(9)(10)

6d*

Three stages

Interval 1 week

Schmid,

MR.

2012a29

RCT Double


25


22:40-

6:40/23:20-

7:20

GSM 900 MHz

2, 8, 14 or 217 Hz

(1)(2)(3)(4)(5

)(6)(7)(9)(10)

6d*

Two stages

Interval 1 week

Schmid,

MR.

2012b43

RCT Double


29


22:40-

6:40/23:20-

7:20

1) Magnetic field (2Hz pulsed)

2) RF 900 MHz

(Modulation 2 Hz, 8 Hz

and harmonicso20 Hz)

(1)(2)(3)(4)(5

)(6)(7)(9)(10)

6d*

Two stages

Interval 1 week

Wagner,

P.

199844

RCT Double

blind Germany 18-37

22

(22-22) 22 males All night 23:00-7:00

GSM 900

217 Hz

Handset-like signal

(1)(2)(3)(4)(5

)(7)(8)(9)(10)

3d*

One stages

Wagner,

P.

200045

RCT Double

blind Germany 20.0 ± 4.0

20

(20-20) 20 males All night 23:00-7:00

GSM 900

217 Hz

Handset-like signal

(1)(2)(3)(4)(5

)(7)(8)(9)(10)

(11)

3d*

Three stages

Interval 1 week



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Table 2. Effects by subgroup analysis

Project Indexes Subgroups No. of studies/Sample SMD or MD (95% CI) I2(%) P value

Sleep

quality

indexes

Sleep latency The sample content ≥25 persons 4/134 0.20 (-0.04, 0.44) 0 0.11

The sample content <25 persons 12/206 0.18 (-0.24, 0.60) 77 0.41

REM sleep latency The Germany people 6/107 3.02 (-1.62, 7.67) 0 0.20

Not the Germany people 11/279 1.02 (-1.77, 3.82) 89 0.47

Waking in the sleep With subjects over 35 years of age 3/90 -0.06 (-0.36, 0.23) 0 0.67

Without subjects over 35 years of age 10/209 0.03 (-0.72, 0.78) 92 0.94

Movement time Pulse-modulated 2/29 -0.19 (-0.71, 0.33) 0 0.48

Non-pulse-modulated 5/107 -0.35 (-1.03, 0.33) 83 0.32

Arousal index (per hour) 217 Hz 4/128 0.16 (-0.30, 0.63) 67 0.49

Non-217 Hz 2/32 1.22 (0.68, 1.76) 0 <0.0001

Sleep efficiency GSM 900 8/196 -0.12 (-0.28, 0.04) 0 0.14

No GSM 900 4/100 -0.31 (-1.19, 0.57) 88 0.49

Sleep

staging

indexes

REM sleep With subjects over 35 years of age 5/150 -0.17 (-0.40, 0.06) 1 0.15

Without subjects over 35 years of age 10/197 -0.39 (-1.11, 0.33) 91 0.29

SWS

Not had subgroup analysis

Stage 1 RF exposure before sleep 3/114 0.32 (0.05, 0.60) 7 0.02

RF exposure all night 7/131 -0.01 (-0.41, 0.38) 59 0.94

Stage 2 The Germany people 6/107 0.06 (-0.21, 0.33) 0 0.68

Not the Germany people 8/221 0.48 (-0.16, 1.13) 90 0.14

TST Article before 2000 5/94 4.80 (3.70, 5.90) 0 <0.0001

Article after 2001 9/244 -2.56 (-4.25, -0.87) 76 0.003

SPT

Not had subgroup analysis



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Subgroup analysis results showed that the

effectiveness of exposure RF radiation for sleep

outcomes was significant for both the articles

published before 2000 and the articles published

after 2001. Stage 1 time (RF radiation before sleep)

was extended in the RF radiation group (MD, 0.91

[0.32, 1.50]; P = 0.003). No statistically significant

differences were found in RF radiation in all night

subgroups. Additionally, no statistically significant

differences in REM sleep (with subjects over 35

years of age or without subjects over 35 years of age)

and stage 2 (RF radiation exposure is before sleep or

all night) were found. Details are shown in Table 2.

3.4. Effects of RF radiation on sleep quality

indexes

The exposure to the cell phone RF radiation

revealed no significant effects on sleep quality

indexes including sleep latency, REM sleep latency,

waking during sleep, movement time, arousal index

(per hour), and sleep efficiency. The details could be

seen in Figure 4. Subgroup analysis indicated that the

non-217Hz RF could increase arousal index (per

hour) (SMD, 1.22 [0.68, 1.76]; P < 0.001). The

217Hz RF had no significant impact on arousal index

(per hour). In the other subgroups, no significant

difference was found between experiments groups

and control groups.

4. Discussion

Our research provided evidence that short-term

exposure to cell phone RF radiation had no impacts

on people's sleep outcomes (including sleep staging

indexes and sleep quality indexes). In previous

studies, many results had shown that cell phone RF

exposure had effects on sleep outcomes, but whether

the effects were harmful to the body remained

unclear. For example, some researchers had found

that prolonged RF radiation could change SWS time

and stage 2[16, 17], or minimized frequency of

waking during sleep[27]. In addition, exposure to RF

radiation could reduce the REM sleep latency[28, 29].

Others believed that exposure to RF radiation could

prolong REM sleep latency[18]. However, there

were also many other studies which showed that RF

radiation had no effects on sleep outcomes[19-23].

An one-year cohort study by Evelyn Mohler showed

that RF-EMF exposure in the environment (including

cell phones) had no effects on sleep quality[30].

Therefore, it was important to analyze these studies,

and our findings provide a comprehensive analysis of

the results of all RCT trials.

In general, global system for mobile

communications (GSM) cell phone generates 217Hz

electromagnetic field. In other cases, GSM cell

phone also generates magnetic field of other

frequencies such as low-frequency radios or high-

frequency radios. Pall's research showed that low

frequency RF could cause a wide range of changes in

the nervous system, resulting in a variety of mental

symptoms or nerve dysfunction including sleep

disorders[31, 32]. Our analysis had shown that the

non-217Hz RF could increase the arousal index (per

hour). Pall's research was supported by the non-

217Hz subgroup containing low-frequency radios

such as 2, 4, and 8Hz in our results. In addition,

Huber[33, 34] found that pulsed RF EMF could alter

the awake and sleep state of EEG. As mentioned

above, the equipments and frequencies used in

different experiments were different. The operating

frequencies of cell phones such as 217Hz RF

radiation could affect the level of electromagnetic

absorption of the human brain[35]. However, the

overall results mask this effect because of all

radiation at frequencies incorporated in our study.

Therefore, we believe that non-217Hz frequency

radio frequencies may reduce sleep quality.

Our data suggest that the cell phone RF radiation

could increase TST in the articles published before

2000 (MD: 4.80). And cell phone RF radiation could

decrease TST in the articles published after 2001

(MD: -2.56). The reason may be the difference in

results caused by changes in mobile communication

networks. Around 2000, cell phone communication

had changed from a 2G network to a 3G network,

and its frequency and mode of occurrence had also

changed. Today, 4G and 5G networks were gradually

evolving, however relevant research data was lack.

Moreover, it was a common phenomenon for people

to use cell phones before going to bed, which will

inevitably lose sleep time[36]. Therefore, we could

only think that this result may be related to the

change of mobile communication technology and

cell phone user's habit. Some research had shown

that insufficient sleep was associated with decreased

alertness and impairment of cognitive ability[37]. In

addition, sufficient sleep could improve sustained

attention and reduce sleep pressure. So, the

shortening of the TST time caused by the RF

radiation from cell phones should also attract

people's attention.

Finally, stage 1 represents the stage before the

sleep begins, which means that using the phone

before going to bed could cause a delay in sleep. We

believed that RF radiation may affect stage1 by

stimulating the brain nervous system. Indeed, in the

current study, the exposure time and the process of

"exposure to cell phone RF radiation" in different

experiments were quite different. One possible

explanation was that the effects was not constant and

ever changing throughout the night, so the level of

significance may not always be reached, especially

considering individual differences in response. So,

the result of "RF exposure all night" was not



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statistically significant, but "RF exposure before

sleep" shows its effects because time and process

were relatively constant. In addition, the combined

effects of contact time and the contact method

(process) of cell phone RF radiation to people sleep

require further research.

The effects of radiofrequency radiation from cell

phones on sleep outcomes were influenced by many

other factors. For example, we suspect that the

prolonged use of a cell phone may lead to changes in

sleep habits. During a short period of time, subjects

may not be able to effectively adjust their sleep

habits when exposed to cellular RF radiation, which

resulted in differences in outcomes. However, there

was currently no relevant placebo-controlled study,

so further research was needed. Equipment and RF

frequencies used in the experiment were not exactly

the same. Some researchers used GSM 900 or GSM

1800, some used 217Hz RF or not. Some studies

used pulse-modulated RF, others used hand base

signals. Researches showed that when the distance

between the brain and the RF radiation point was

40cm[17], the REM sleep was extended, and when

the distance was 3 meters[22], the influence

disappears. In the studies that we included, the

distance between the radiation points and the brain

was not identical. So, this distance may also be a

potential factor affecting sleep outcomes.

The results of this study were meaningful. Above

all, all experiments included were double-blind,

randomized controlled studies. Although meta-

analysis found significant heterogeneity between

studies, further sensitivity analyses and publication

bias tests favored the coherence effects among

different populations. Next, the experiments

conducted in different countries and regions followed

the same design method. Thirdly, polysomnography

analyzer was used to objectively record sleep

outcome indicators. Therefore, we had reason to

believe that at least the overall role of the radio band

(short-time) included in this study does not had much

impacts on human sleep. These results were

important in guiding the current assessment of

evidences and the formulation of public health

strategies.

We analyzed the overall results of previous studies

through systematic quality assessments for the first

time and concluded from the subgroup that different

RF exposure times and frequencies may had impacts

on total sleep time, number of awakenings during

sleep, and time to fall asleep. However, our analysis

still had some limitations. First, the results of the

data assessment were a synthesis of the results

contained only in our study. Second, the research

project did not involve the use of the screen blue

light of cell phones on the quality of sleep, because

they were not within the evaluation range. Third,

although our studies were all RCT studies, the

confusion and bias could not be completely avoided.

Finally, all studies were from developed countries,

we do not know the specific situations in developing

countries. Even so, the study could serve as a guide

for the use of cell phones to encourage young people

to appropriately reduce the use of cell phones, and

ensure adequate sleep. At present, experimental data

on the effects of long-term radiofrequency radiation

on sleep are lacking. No one has done research on

the susceptibility of sleep disturbance caused by RF

radiation, which may be the future research

directions.

5. Conclusions

In this meta-analysis, there was no statistically

significant association between RF exposure and

sleep outcomes. Therefore, at least in our study, we

believe that short-term exposure to mobile phone RF

radiation had no effects on sleep outcomes. However,

considering the impact of mobile phone usage time

and non-RF radiation factors on sleep, we

recommend to rationalize the use of mobile phones

and develop good sleep hygiene habits.

Author Contributions The abstracts of citations obtained from the

primary broad search were read independently by

reviewers Han Zhou, Feng Zhong, Rui Xu, Cuiping

Liu and Kunxiang Ding to identify potentially

eligible studies. Full-text articles of these studies

were obtained and assessed for eligibility by

reviewers Han Zhou, Feng Zhong, and Rui Xu

independently, using the predefined eligibility

criteria. Differences in opinion were resolved by

panel discussion to reach a consistent result. To avoid

duplication of data, care was taken to ensure that

multiple publications of the same study were

excluded.

Funding No Funding

Conflicts of Interest None declared

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