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Lee's Wiki Project for Methods in Cognitive and Brain Research

Electronic media and sleep

(There's a recycled paragraph here introducing the topic)

Effects on sleep
Studies into the effects of electronic media-use and sleep reveal a number of adverse effects to the sleep of those who have interacted with devices compared to those who have not. For instance, (recycled study). In fact, a number of studies show electronic media use before bed can prolong the time it takes to initiate sleep (sleep onset latency), cause a shorter total sleep time and a later wake-up time,  and alter brain activity during every stage of sleep - stages 1-3 as well as REM sleep:
 * Sleep onset latency – as defined by Carskadon and Dement, sleep onset latency refers to the time between “lights out” and the first epoch of any stage of sleep. Correlation studies show a relationship between excessive phone use and an increased onset latency, i.e. it takes longer to fall asleep following increased media use.
 * Stages 1 and 2 (light sleep) – simply having an electronic device in the bedroom of a sleeper emitting wireless communication signals (a mobile phone, for example) extended the periods in these first two stages which can lead to increased sleep disturbances. Although more time is spent in these phases than normal following electronic media exposure, there are less sleep spindles witnessed in EEG during stage 2. These spikes of activity inhibit other brain processes from occurring to assist one in getting into later stages of the sleep cycle
 * Stages 3 (deep sleep) – during stage 3, human growth hormone (HGH) is released and the physical recovery from daily wear and tear occurs. The stage is characterised by the observation of slow delta brainwaves through sleep physiology devices such as a polysomnogram. Radio frequency (RF) emissions from tablets and mobile phones have been shown to reduce the overall time in this stage of sleep
 * REM sleep – similar to stage 3, REM sleep has been shown to be reduced following reading from an eBook in the hours before bed. REM sleep is another restorative phase undergone during the sleep cycle and neuropsychological studies reveal deficits in overall brain size, cerebral blood flow to the pons and superior frontal regions, and cerebral metabolic rates for glucose following prolonged REM sleep deprivation.

(Recycled paragraph about how long adults are supposed to sleep for and about the risks of obesity, diabetes, etc.)

Mechanisms
(Recycled study and explanation here) as well as define some potential mechanisms in which electronics use disrupts sleep. The publishers listed three physiological mechanisms along with the prospect of electronic media directly displacing sleep (i.e. playing video games instead of sleeping).

Hyperarousal
Reports suggest that electronic media, particularly video games, have the ability to induce a state of heightened arousal (cognitively and/or physiologically) which increases mood, attention and reaction time around bed – inhibiting sleep onset. Studies into hyperarousal and sleep are hard to translate due to the mix in results. For example, (recycled study). In a similar method, Weaver et al. presents a case in which the sleep of thirteen adolescents was compared following playing Call of Duty 4: Modern Warfare – a fast-paced first-person shooter – to watching March of the Penguins – described by the authors as a “decidedly tranquil viewing experience” – for 50 minutes prior to bed. The researchers measured physiological arousal through the participant’s heart rate (using an oximeter finger pulse probe) and cognitive alertness through alpha power on electroencephalography (EEG), electrooculography (EOG), and electromyography (EMG), respectively. Results shown that there were no differences in the heart rates or alpha waves pre-sleep and sleep architecture was the same between the participants, regardless of whether they watched the DVD or played the video game.

Blue light theory
(Recycled few sentences on melatonin). The body’s natural sleep cycle (the circadian rhythm) is what describes the natural fluctuation of the body’s melatonin levels and is regulated by light. Different wavelengths of light have different effects on melatonin – low frequency, long wavelengths of light such as red and orange light cause increases in melatonin secretion, causing sleepiness, and these wavelengths are prominent during the setting sun and night conditions. Whereas high frequency, short wavelengths of light (such as violet and blue) suppress melatonin production and results in a feeling of wakefulness – these wavelengths are more prominent during the rising sun and daytime. The circadian rhythm helps the body to know when it’s time to go to sleep and when it’s time to wake up but electronic media devices use light-emitting diodes (LEDs) that emit large proportions of blue light. It is possible that these devices can disrupt the natural circadian rhythm.

(Recycled study). Moreover, half of the participants that took part in a random trial subjectively reported better mood and quality of sleep following two weeks of using blue-light blocking glasses for 3 hours before bed than a control group who made no changes to bedtime routines.

Electromagnetic radiation
Electronic media devices emit electromagnetic radiation in varying forms. Mobile phones and tablets, in particular, produce radio waves (the same ones that allow the device’s calling and texting capabilities). A number of studies listed in the Cain and Gradisar review shown that merely the presence of electronics in the bedroom during sleep may negatively impact sleep. Specifically, a 2011 study revealed how exposure to 884MHz of RF waves (lower end of mobile phone output) negatively affected the sleep of its participants as the onset of stage 3 sleep was prolonged as well as reduced in time, and stage 2 (light sleep) was increased. Furthermore, brain activity power was elevated during the first two hours of stage 2 sleep, indicating that participants could easily be woken by external stimuli. Likewise, the same magnitude of RF exposure produced a prolonged time to reach deep sleep, enhanced cognitive performance, and resulted in more headaches complaints in participants when compared to those exposed to a non-RF sham in another study.

However, with regards to melatonin levels, electromagnetic radiation may fall short of a comprehensive explanation for lowering sleep quality as another study revealed, although there was a delay in the onset of melatonin, no differences in the total nighttime melatonin output were found between that of participants exposed to mobile phone emissions and that of controls.

Work and academic performance
Students may exhibit adverse effects in academic performance following circadian rhythm alterations as Trockel et al. found that the largest amount of variance in students’ grade point averages was attributed to sleep habits, particularly wake-up times As well as this, one study in a hospital setting found that there was a 36% increase in the rate of serious medical errors, twice as many attention errors and 300% more fatigue-related medical errors committed by interns working 16-hour night shifts compared to those that work 16-hour days

Traffic collisions
When studying alterations to circadian rhythm, researchers commonly refer to Spring-time DST clock changes. Studying the rates of traffic collisions in the days and weeks following losing an hour of sleep, researchers have found:
 * Traffic-related injuries increase by up to 8% for up to 2 weeks following Spring DST
 * The first Monday after Spring DST has a large increase in traffic accidents as well as traffic-related fatalities

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