I stay up past my bedtime
Why do you need to stay up so late?
I'm affected by my mood-doesn't matter what the weather is.
I'm sorry you're not in the right mood, but you still have to sleep properly to have a healthy mind and body. You parents give you a bedtime because they care about you and want you to be your best. Don't disobey that and get sick.
You're right. I'm going to bed now.
It is good that you are willing to do what it takes to keep you healthy. Keeping a proper bedtime is an important aspect of that.