I think it has different meanings with different subjects. ”你要睡觉“means "you should sleep". 他/我要睡觉 both want and will are OK. It depends on the context.

means" i'll sleep." "i want to sleep." you can say "我想睡觉了。“

Thanks friend i'll practice these differents ways to say it :D

根据你的情况来选择： - I'll sleep= 我即将要睡觉 - I want to sleep=我想睡觉 - I'm going to sleep=我正准备睡觉

Thank u v much who answered jaja :D