MacBook waking while lid is closed
“If you have ever had your MacBook or MacBook Pro inexplicably wake while the lid is closed, there is a good probability that Bluetooth may be the culprit. If you have Bluetooth enabled, there is a default setting ‘Allow Bluetooth devices to wake this computer’ that is checked ‘On’.
I have found that if you uncheck this box, unwarranted waking from sleep stops."
Sr. Systems Engineer
Higher Education Division, Apple
(Quoted from email with permission.)