Well there is a physiological reason as well. Lifestyle training though years of repeatedly pushing the sleep envelope (trying to stay up for whatever reason as a kid, and then as a young adult, i.e., drinking Monster or playing videos) conditions the brain activity to intepret the dropping of your brrainwaves from beta to alpha as indicatinmg final resolution to enter sleep mode.
For the most creative people, and people who can pray, or even meditate for long periods, entering alpha while remaining awake or conscious is normative. Alpha generally is not indicative of sleep mode (delta is) but if one had trained themselves (even unintentionally) in such a way that the only time they slow down the activity of hyper-thought is when they are going to bed, then this condition results.
To overrcome this one must practice entering the alpha realm with the pro-active intention of staying awake. It was once thought to be impossioble as this is part of our autonomic response system. But now we know it can be effected and even controlled through practice and biofeedback. One can do this through (before doing something) taking prayer time of no less than a two or three full minutes (a feat many never do) and then engage an activity. One can sit up straight, close their eyes and take a few slow but deep (belly expanding) breaths and then let the thoughts slow to stillness and then get up and do something active. In fact it has even been shown in studies that if one takes a few moments to calm down their mind before studying and then repeats this before testing one scores better by average over the long run.