Electronic media and sleep

The use of computers (including devices such as smart phones) before bed has been associated with a reduction in the hours of sleep experienced by frequent users, along with a decreased quality of sleep. The results of computer use at night have been linked with a myriad of negative consequences because of reduced sleep, ranging from an increase in obesity to a lack of energy during the day. Evidence suggests that this could be avoided by limiting computer use prior to sleep.

Basics of sleep needs
An adult is expected to sleep 7–9 hours per night to be properly rested, while adolescents from the age of 10-17 need 8.5-9.5 hours of sleep, with the hours needed decreasing with increased age. Failing to meet these sleep needs has been linked with depression, obesity, diabetes, and cardiovascular disease.

An important factor in sleep is melatonin, a hormone produced in the pineal gland that is associated with sleep facilitation. During the daytime, blood melatonin levels are barely detectable, but at night, melatonin levels are high. This phenomenon is due to light's effect on melatonin production. If there is sufficient light, then melatonin production is halted. It is possible for artificial light to be bright enough to have this effect.

Melatonin is not the only component of sleep facilitation. Activities performed on electronics can stimulate the brain, so that the user does not become relaxed, and so is unable to sleep. Choosing another activity, such as reading, may enhance sleep.

Sleep statistics
According to a poll conducted in 2011 by the National Sleep Foundation:
 * 60% of people aged 13–64 experience problems sleeping either nightly, or almost nightly.
 * 63% of Americans do not feel they receive enough sleep during the week.
 * 15% of people aged 19–64 receive less than 6 hours on weeknights
 * 95% of participants used electronics in the hour before sleep multiple times a week, with 61% using computers (whether desktop or laptop)
 * 40% of Americans can be classified as severely sleep deprived.

Video games and arousal
In a 2012 study, “The impact of prolonged violent video-gaming on adolescent sleep: an experimental study”, 17 adolescents were told to play a violent video game before going to bed. They were split into groups with 50 minutes or 150 minutes of game play. There was no discernible difference in heart rate during game play and after. However, the group of longer game video game play sessions experienced both a lowering in the quantity and the quality of sleep. In the case of sleep quality, participants experienced a loss of REM sleep, or rapid eye movement sleep, important for encoding new information from short term to long term memories. This study however did not link the sleep reduction experienced to physical arousal, which in this study was measured through heart rate.

A 2010 study, “Electronic media use and sleep in school-aged children and adolescents: a review”, took 36 published papers and attempted to find links between electronic use and sleep loss. Through the meta analysis of the studies, the study hoped to be able to better pinpoint the cause of sleep loss, in order to establish causation(s) rather than simply correlation. Electronics involved included televisions, computers, electronic games, internet devices, cell phones, and music devices.

Although the study was unable to make definitive conclusions about the cause of sleep loss, it provided evidence that electronics use before bed had a negative impact on sleep. Media overuse has been the most strongly associated with sleep loss. The mere presence of electronics in the room during sleep has also been shown to negatively impact sleep.

Self-luminous tablets
A 2012 study, “Light level and duration of exposure determine the impact of self-luminous tablets on melatonin suppression”, showed that melatonin levels are suppressed by roughly 22% when someone is exposed to backlit screens for two hours.

The study was done at the Lightning Research Center at the Rensselaer Polytechnic Institute, by a research team lead by Mariana Figuerio, an associate professor at the institute.

In this study, 13 participants used backlit devices for 2 hours, and were divided into a group that wore goggles with 470-nm (blue) light emitted from LEDs, a group that wore orange tinted glasses, and a group that did not wear any headgear. 470-nm light has been shown to suppress melatonin, while the orange tinted glasses have been shown to filter out short-wavelength radiation, thus not suppressing melatonin.

The tablets were then turned on, with their displays at full brightness. The conclusions from the study were that with only one hour of use, there was no significant melatonin suppression. However, two hours of use did lead to significant melatonin suppression. The study also showed that the level of brightness of the light impacted how much melatonin was suppressed. The brighter the screen, the more melatonin was suppressed. This was measured by Dimesimeters being put close to the eye to measure individual light exposure. This was to control for the differing amounts of light received by different individuals, as participants did not perform the same activities on the tablets. Both the length of exposure to the screen and the distance to the screen from the eye were noted, as they indicated the amount of light that would come in contact with the back of the eye.

Of note, display screens are becoming progressively brighter, and the increase in white light produced means that more short wavelengths lights are being emitted. It is the short wavelengths of lights at suppress and delay melatonin production. The light emissions from the tablet varied from 5 lux to over 50 lux. While 5 lux will most likely not impact melatonin levels, light levels over 50 lux over the duration of two hours decreases melatonin levels.

Impact of computer-use related sleep loss
Many issues stem from a lack of sleep, such as:
 * Difficulties encoding new memories
 * Weight gain, including obesity
 * Depression and other mood disorder, or irritability
 * Cardiovascular Diseases
 * Lowering of immune function
 * Diabetes
 * Symptoms of anxiety

What can be done to improve sleep
To improve the quality of sleep, one can avoid bright lights around bed time, allowing for the production of melatonin. This means avoiding electronics about an hour before bed time. If that is not possible, dimming the screen brightness may improve sleep, as the degree of brightness is associated with how much melatonin production is suppressed. It should be noted, however, that computer use is not the only culprit in problems sleeping. Some other possible culprits include stress and caffeine, among many others. For further information on sleep, the National Sleep Foundation contains a great deal of information.