We all have different levels of anxiety. Some of us can't sleep all night knowing that tomorrow something will happen, even something not very important, and some of us are engaged in illegal activities, cheat and kill people and still sleep well. It is quite possible that OP has a high level of anxiety, so I would recommend him to be examined. If the examination shows that his anxiety level is high, it can be reduced by medication. If it happens only when gambling, he can try to reduce his bet.