How do I determine what is waking my machine up? Recently my Macbook Pro has been waking up from sleep at undesirable times (middle of the night) without any user interaction (nobody has touched it).

Is there a log on the machine that records the reason a machine woke from sleep?

Apparently the machine wakes up because:

1/26/14, 1:21:20 AM PST  Wake  Wake [CDNVA] due to EHC1/HID Activity: Using AC (Charge:99%)


What is [CDNVA] due to EHC1/HID Activity: Using AC (Charge:99%)?
You can find a lot of information in the system log.

Open the Console utility and this will allow you to easily search the system log for "sleep" and "wake".

The information is not easy to understand but if you do find some lines in the system log you can't understand feel free to update your question.

EHC1 is usually something to do with a USB device. Do you have an external drive attached to the machine? Is it powered via USB?