This is a study finding that physiological smartphone withdrawal doesn't exist. Smartphone dependence is merely "psychological-behavioural," and you can develop a psychologically dependent relationship with anything. Being dependant on your girlfriend doesn't make you "addicted" to her. Please, find 10 more studies—this is making my point for me.

Again, I'm not saying our relationship with smartphones is healthy. I'm saying addiction is a specific thing, and this isn't it. Getting strung out on heroin is not anything like using your phone too much.