Your thoughts are like a picture shown on a screen. It is continuous and perinial.
Your concious effort can only arrest it, for you to ponder over. This is your time for contemplation and thought processesing.
I said all this, for you to appreciate, that there is no such thing as day and night thoughts. You are a victim or a witness of happenings and accordingly your thoughts are formed.
You have to go with the flow of life, to enjoy whatever is offered to you, to be happy and joyous. All the best.