How should I respond to the question 'How would you handle down time?' at an interview?

Short story: I applied for a security officer job a few months ago, they didn't hire me at the time, so I reapplied recently and I have another initial interview tomorrow. This was the only question I wasn't really sure how to answer, so any tips?

Initially I had said "I handle down time well; at my current job when we have down time I try to find something extra to do - cleaning or prepping to help pass the time so I can still stay alert." Should I just stick to something like that?

And by 'down time' I mean time when the workers don't really have anything happening but they're on their shift - not on break or anything. My boyfriend's friend works for the same company and he said that some people do homework or text, but I can't exactly say that in an interview..