Why are you asking? If you want to save battery then it will make very little difference as it's low power. A majority of your battery will go during activities so just don't worry about turning it off. If you have another reason let us know
As CW said, the battery drain is minimal (I've got a couple devices with WHR). When I first got one, I was a bit concerned about the battery, but that was a year ago now, and I found it's not an issue.