Whilst genetic factors clearly play a role, it is not yet clear exactly what causes ADHD, but research clearly indicates there are problems with the function of key areas of the brain involved with attention and impulse-control.
On reviewing the literature it’s clear that mental health disorders are more often than not tied to poor sleep quality and disrupted circadian rhythms. Our circadian rhythms are tied to the natural cycles of light and dark which means the wrong type of light at the wrong time of day or night can disrupt our circadian rhythms and thereby impact our sleep negatively.