Maybe not as much as we think, as AFAIK diabetes, obesity, depression/addiction and mental illness (for example) are also hitting hard among youngsters.
GIGO (Garbage In, Garbage Out) rules. Add sleep (of dubious quality) deprivation, 'bad stress' (no real motivation, extreme noise and light, near-constant state of haste...), lack of exercise... feedback-boosting the destructive process we now see nearly everywhere in full swing.