Occurring approximately one hour into our sleep time, rapid eye movement (REM) sleep is important for consolidating memories, processing emotions, and the development of the brain (via the Sleep Foundation). REM sleep is also where most of our most vivid dreams occur. According to a 2012 study published in Frontiers in Behavioral Neurosciences, deprivation of REM sleep played a role in regulating emotions and memory properly.
The light emitted by electronics, including televisions, can interfere with our being able to successfully reach the REM stage of sleep, as reported by a 2014 study published in PNAS. In that study, patients who used electronics before bed took ten minutes longer to fall asleep than those who didn’t. Once they fell asleep, they also experienced far less rapid eye movement. In addition, our brains continue to process information even after we have fallen asleep, as reported by a 2014 study published in Current Biology. Because of this, sounds, music, and dialogue coming from the TV may cause our brains to react, keeping us from falling into a deeper, more restful sleep.