Shir, beth is right. You will know.
I was exhausted when I went to bed last night around 10 I think. It must have been a sound sleep because I woke up at about 3:30 this morning and there was no going back to sleep. Gave up at 5 and just got up and made coffee. This is ok and I have done a lot of work, but I have a feeling I will be nodding out about 8 tonight. Why did my body decide early to bed early to rise was a good idea? It makes me feel old.