Training the brain to anticipate anxiety from checking phones upon waking reduces deep sleep at night, leading to shallow sleep.

“and I think a very maligned sort of version of it happens with our phones because most people the first thing that they do when they wake up in the morning is swipe and they just unlock this world of anxiety that comes flooding in through their phone emails texts social media you essentially are training your brain to anticipate that wave of anxiety every morning and what we've discovered is that when you embed that anticipatory expectation in the morning the amount of deep sleep that you get at night is less you end up sleeping in a shallow state and you don't get the same amount of deep sleep”