Aside from putting your smartphone out of reach to be distanced from alerts, I make sure my phone is on airplane mode when I'm asleep or resting. This completely blocks me from any contact, and more importantly, stops the cell phone waves that may potentially disrupt our brain wave patterns/be unhealthy for us.
While wireless is everywhere around us, it's one less major beacon to worry about. With it offline, there's no urge for me to check my phone unless I manually want to, and a solid sleep usually feels too valuable to disrupt for a peek at what's popped up in my phone, which I won't get to until the next day anyway.