Sleeping with your cell phone is a bad idea for a few reasons. First, keeping your phone under your pillow could build up heat and present a potential fire hazard, especially if your phone is charging or has a defect. It’s also known that the LED light from phone screens can disrupt melatonin production and circadian rhythms, hurting your sleep quality, according to the National Sleep Foundation. And, of course, there’s also radiation to consider as well. The amounts of radiofrequency radiation cell phones give off are the same ones emitted from microwaves. There is also concern about the safety of cell phone use with respect to cancer and brain tumors, per the American Cancer Society.