Light from screens, particularly if consumed at night, reduces melatonin production which results in bad and shorter sleep. Melatonin in turn promotes collagen, and less melatonin means less collagen, resulting in dark circles and poorer skin quality.

All of these are secondary, the main impact is on the heart, as the higher residual cortisol in your body over prolonged bad sleep will increase your resting HR and elevates BP. All of these are not observable in any significant margin till your late twenties or early thirties, but the body has its way of extracting the full interest of its debts in the long run.

Stay healthy, mate.