The main reason why a lot of people find it difficult to sleep after winning is because they are under a lot of anxiety. There's a type of anxiety you can feel when you are handling a certain amount of money especially if you haven't won that amount before, gambling can make you overthink about how you are going to spend or use that money. This is the reason why self control is very important as a gambler
What has self control got to do with thinking of what to do with the money you genuinely won through gambling? I thought self control is only applicable when a person is still gambling, and maybe after winning too since the gambler may likely be tempted to still continue gambling from the money won which likely lead to him or her losing the money.
But when it comes to staying awake and being unable to find sleep simply after winning a huge sum of money and you are thinking of what to do with the money, there is nothing like self control here.
And besides, it's even a mistake to not have any plan on ground for what a huge sum of money will be used for if and when it comes, it's mistake because without having such plans on ground beforehand, there is a high chance that the money will end up being spent recklessly without proper planning.