Even more important, I think, is don't check your devices when you go to bed. What you need is a solid night's sleep in order to be productive the next day; not to zoom into "reaction mode" when you are in your pajamas. I would go even further and suggest you not check your devices after dinner. I have lost count of the sleepless nights I have endured over some complaint, query, or upsetting e-mail, text, news story or whatever.