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Possible Mechanisms for the association between Digital Media and Sleep Disturbances

Several mechanisms (biological and psycho-social) have been suggested to explain how digital media use might impair sleep duration and quality

 

Association between Digital Media Use &Sleep Quality:Possible Mechanisms

 

Sleeping time postponement – digital media use during the night causes shortened sleep duration. Use around the time of going to sleep or after lights out may also create difficulty falling asleep and reduction in sleep duration. At the same time, engaging in other activities at night, including homework, reading and late night socializing may also take up sleep time.

 

Physical, mental and social arousal – digital media exposure increases physical, mental or social arousal which may influence sleep quality, both due to the act of using digital media and as a function of the contents. For example, violent digital games, positive or negative reactions in social media and provocative information before sleep might increase physical or mental arousal and impair the ability to fall asleep or to sleep through the night. In addition, communication via social media causes expectation of receiving an immediate reaction and sensation of urgency. Results of a study comparing several sleep indices between 7 participants who played arousing computer games (war games) before going to sleep versus those who performed other simple tasks on the computer at the same time showed that the type of task (arousing or relaxing) influenced sleep indices.

 

Light exposure during the night and exposure to RF (radiofrequency) radiation emitted by various devices were suggested as biological mechanisms acting on melatonin secretion and on the Circadian cycle.

 

Exposure to light emitted by devices - When digital devices are used there is exposure to light from the screen during the hours of darkness, which might impair the sleep (Circadian) cycle. Studies have found that shortwave light such as the visible blue light emitted from digital devices, may influence melatonin secretion, sleep onset latency, sleep architecture and quality. It should be noted that these findings are controversial.

In a study that examined the degree of wakefulness in the pre-sleep period, during sleep and in the morning, in 16 adolescents (aged 14-19), three types of screens of different clarity were used, one hour before sleep time. No significant differences were found in wakefulness and it was suggested that the effect may be dependent on dosage and frequency of exposure and not only on the type of light exposure. In another study, the effect of night time light on indices such as melatonin level (in saliva), core body temperature and sleep rhythm tendencies (total sum of sleep cycle durations on EEG) amongst 9 participants undergoing polysomnography was investigated. It was found that exposure to white light caused delay in melatonin secretion cycles, and change in body temperature and sleep rhythm tendencies.

In the summary by the expert committee of the European Commission from 2011 on the subject of health effects of artificial light, it was suggested that the effect of blue light on melatonin production suppression is high compared to other types of light. The expert committee noted that because of the paucity of studies dealing with the association between light exposure and sleep, it is difficult to draw conclusions. It was further noted in the committee’s summary that exposure of the public to this type of light is uncommon.

In a report published by the French Agency for Food, Environmental and Occupational Health & Safety (ANSES) possible effects of exposure to light seen in LED bulbs as a result of impairment of biological clock regulation were described. The situation may be severe when high color temperature LED bulbs are used (“cold” white or blue). The regulation impairment might affect metabolism, the thymus (depression, mood) and the sleep/wake cycle. Furthermore, there may be an effect from penetration of large amounts of light due to insufficient pupil contraction, and due to this, additional increase in the risk of exposure to blue light.

An Israeli study published in 2017 examined how artificial light emitted from screens affects sleep quality. During the study 19 participants were exposed to LED 22 inch computer screens for two hours during the evening with varying conditions of wavelength and intensity. It was found that short wavelength (blue light) emitted by computer screens interrupts sleep continuity and quality. Amongst other observations, a reduction in sleep duration was observed and there was an increase in the number of night time awakenings because of exposure to short wavelengths. It was also seen that melatonin secretion suppression was greater under exposure to short wavelength (blue) compared to exposure to long wavelength (red). The natural drop in body temperature during sleep was also impaired due to exposure to short wavelength. Accordingly the feeling of sleepiness was found to be greater and there was morning attention impairment after exposure to short wavelength. The wave intensity also had an effect on sleep, but this was less compared to the effect of wavelength on sleep.

 

Exposure to RF non ionizing radiation emitted by devices - It has been suggested that exposure to electromagnetic field in the radiofrequency range has an effect on sleep architecture. Night time exposure to non-ionizing radiation emitted by devices has been found to be associated with changes in sleep architecture and postponement of melatonin secretion. At the same time, the existing information today is minimal and there are studies that did not manage to demonstrate this association.

In a study that investigated the effect of exposure to radiation pulses (at cellphone frequencies ) during sleep on EEG waves and motor performance amongst 16 participants, an effect was demonstrated on slow wave activity during exposure, around the end of sleep cycles. There was also a 20% reduction in improvement in motor performances after sleep. The researchers concluded that there may be an association between exposure and impairment in wakefulness expected after sleep. Another study investigated the association between level of exposure to radiation and EEG recordings in 15 participants exposed to various intensities of radiation (0.2 W/kg and 5 W/kg) for 30 minutes prior to sleep, compared to a control group who were not exposed to radiation (at a frequency of  900 MHz, and to pulses with GSM broadcast format). During the exposure the participants were requested to perform cognitive tasks and subsequently underwent EEG recordings during 8 hours of sleep. Even though the sleep pattern did not change due to the exposure, on analysis of the EEGs a dose-response relationship was found for EEG wave height during non REM sleep. In some types of cognitive tests there was slowing of reaction speed with increasing radiation intensity. The researchers concluded that exposure to radiation before sleep causes changes in brain activity. There is a dose –response relationship between degree of exposure and effect on non REM sleep and on cognitive performance.

Another study investigated the effect of prolonged 3 hour (including 2 hours of sleep) exposure to radiation in the format of GSM broadcast at 884 MHz frequency in a group of 36 men and 35 women. EEG recordings, cognitive functions and subjective reports were assessed during exposure and without exposure. Exposure was found to affect the EEG recordings (prolongation of sleep latency time). Furthermore there was found to be a correlation between subjective reports (such as headaches) and exposure to radiation.

 

 

 

 

 

*This review was prepared with the assistance and guidance of Prof. Tamar Shochat, The Faculty of Social Welfare and Health Sciences, Haifa University and Mr. Amit Green from the Assuta Health Center Sleep Institute.

 

 

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Updated: 15.7.2018