Interesting, I'll go through stretches where I'll wake up early like that, too. Hadn't thought of biotin as a factor, although I typically eat plenty of cooked eggs.

Here's a related source supporting your experience.

Vitamins To Help with Sleep

Vitamin H is also sometimes known as biotin. It helps regulate and control energy production in your cells and is partially responsible for the bodily function that turns consumed food into energy. Deficiencies of vitamin H may result in insomnia symptoms, according to the University of Maryland Medical Center, including difficulty falling asleep or constantly waking up in the middle of the night. The vitamin is naturally found in cooked eggs, various kinds of nuts and whole grains.

When my hair was falling out I took megadoses of biotin and it worked! I don't remember about the sleep.

I have a question though - is there a way to get more biotin the natural way, without the pills? Is there anything that prevents biotin from getting absorbed?