The use of computers, devices Including Such As smartphones , tablet computers and laptops before bed has-been associated with a reduction in the hours of sleep Experienced by frequent users, along with a Decreased quality of sleep, in MOST cases. The results of computer use have been linked to tiredness. A study conducted by the University of Oxford shows that in 73% of cases, the smartphone is more likely to be used.
Effects on sleep
An adult is expected to sleep 7-9 hours per night to be properly rested, while teens 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 needs has been linked to depression , obesity , diabetes , and cardiovascular disease .  An important factor in sleep is melatonin , a hormone produced in the pineal glandthat is associated with sleep facilitation. During the daytime, blood 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. 
Nuutinen et al demonstrated that the presence of electronic media in children’s bedrooms can reduce sleep and delay.  Electronic media use can increase mental arousal, making it more difficult to fall asleep. Computer use and TV viewing can also affect sleep by slow sleep decreasing sleep , REM sleep and sleep efficiency. 
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 and sleep loss. Through the meta analysis of the studies, the study is more likely to be pinpointed to 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 a negative impact on sleep. Media overuse has been the most strongly associated with sleep loss. Merely the presence of electronics in the room during sleep has been shown to negatively impact sleep. 
In a 2012 study, “The impact of prolonged violent video-gaming on adolescent sleep: an experimental study”, 17 adolescents were told to play violent video games 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 long-running 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 has been studied in this study and has been measured through heart rate. 
A 2012 study, “Light level and duration of exposure of the impact of self-luminous tablets on melatonin suppression”, showed that melatonin levels are suppressed by roughly 22% when being exposed to backlit screens for two hours.  This drop is similar to what would be expected after being exposed to normal sunlight. Exposure to backlit screens for only one hour rather than two hours shown no significant melatonin suppression. 
- Dark therapy
- Delayed sleep phase disorder
- Light effects on circadian rhythm
- Night Shift (software)
- Jump up^ “Sleep and Sleep Disorders” . Centers for Disease Control and Prevention . Centers for Disease Control and Prevention . Retrieved 13 February 2013 .
- Jump up^ “Melatonin and Sleep” . Sleep Foundation . National Sleep Foundation . Retrieved 13 February 2013 .
- Jump up^ Nuutinen, T; Ray, C; Roos, E (2013). “Do computer use, TV viewing, and the presence of the media in the predictable school-aged children’s bedroom in a longitudinal study?” BMC Public Health (13): 684.
- Jump up^ Chen, M; Wang, EK; Jeng, Y (2006). “Adequate sleep among adolescents is positively associated with health status and health-related behaviors”. BMC Public Health (13): 59.
- Jump up^ Cain, Neralie; Michael Gradisar (15 February 2010). “Electronic media use and sleep in school-aged children and adolescents: a review” . Sleep Med . 11 : 735-742. doi : 10.1016 / j.sleep.2010.02.006 . Retrieved 13 February 2013 .
- Jump up^ King, DL; Michael Gradisar; et al. (Nov 9, 2012). “The impact of prolonged violent video-gaming on teenager sleep: an experimental study”. Journal of Sleep Research . 22 : 137-143. doi : 10.1111 / j.1365-2869.2012.01060.x .
- Jump up^ “Light from Self-Luminous Tablet Computers Can Affect Evening Melatonin, Delaying Sleep” . Science Daily . Science Daily . Retrieved 13 February 2013 .
- Jump up^ “Why Do Tablet Tablets Disrupt Sleeping Patterns?” . Medical News Today .