A study conducted at the Rensselaer Polytechnic Institute, found that at least two hours of exposure to a tablet device reduced melatonin, a hormone that helps promotes sleep, levels by twenty-two percent. Melatonin also regulates your internal clock and plays a role in the sleep cycle. This is a concern for researchers since 90 percent of Americans regularly use a computer or electronic device an hour before bedtime. The risk of obesity, diabetes and other disorders is another symptom looming over night time tablet use. Experts recommend limiting computer or tablet time before bed and dimming the screens of these devices as much as possible.