I personally believe that it is real (just go camping where there's no service and you'll feel better) but it's hard to prove without decades of study and money, which won't happen because there's so much money to be made.

There are other reasons why camping makes you feel better. Earthing/grounding gets you in touch with the earth's natural schumann resonance (through the canvas tent) and the fresh air. Also too getting away from distractions.

There's a real study on this, but they don't speculate what the cause it: http://time.com/4656550/camping-sleep-insomnia/