1. YOUR PHONE
Actually, you shouldn't take any electronics to bed and that includes your laptop and e-reader, too. Not only are there some seriously bad side effects of nighttime light exposure (obesity, depression, and insomnia), but it's also a safety hazard. There have been some reports that phones with faulty chargers can catch flame. Plus, any time you hear a buzz, beep, or a light goes off, your sleep is interrupted.
And if not used properly, electric blankets also pose a risk. Make sure to place it on top of your other bedding — never underneath.