I too have never had the "dark circle under the eyes" effect. and yes for me after a good session I do find it easier to sleep. when I was young 5 - 10 yrs old, I often could not go to sleep unless I had a go at bedtime. I was never constantly tired as a result of my habit, though in my older years 40's + I don't seem to have as much energy as other folks I see. that could be due to health issues, age, or my addiction. I do know that when I skip a few days (happens sometimes) that I don't seem any more tired/energetic, or really any difference at all. and I too have never had the "death Grip", in fact if I want something different I will use lube. but that is a rare thing.