Why does waking up make me go to the bathroom?

When I wake up in the middle of the night (3:45-4 AM like friggin clockwork, damn lamotrigine) I’m fine…but then my guts go into overdrive shifting around and gurgling and within 5 minutes I have to go. It’s like a worker getting woken up by his boss and suddenly scrambling to look busy.

One possibility is that you woke up because you had to go.