I have a rather simple question. What is the purpose of false awakenings?

I have had them many times, but I never really thought about WHY they happening. It's like the mind is purposely trying to you. If you are having a nice lucid dream and you really wake up, I can understand that. Maybe it was just time for you to wake up. But a false awakening? It's like the mind is just trying to mess with you. And if it is, why?

I'd like to hear people's opinions on this.

Thanks