An internal alarm clock? For as long as I can remember I have always been able to think: "I need to wake up at 8 am" (or whatever time) and the next morning I would wake up a couple minutes before or a couple minutes after the time I "set". This works 95 percent of the time. I don't rely on it if I have to be up for the kids school, nor did I rely on it when I had to be at work at a specific time, just in case.
Today however it did not work. I planned to be up at 8 am. It was 9:45. Thankfully we didn't have anywhere to be. It is overcast and rainy so I am pretty sure my body and brain thought it was earlier.
So do you have an intermal alarm??