Robyn Kozierok writes:
Seems to me the simplest thing would be a timer to plug the
nightlight into.

The ones we've tried all make a humming or ticking sound that the kids
find objectionable.

Are these all mechanical devices? I found several digital timers
(search for "digital plug-in timer"). I would expect these would be
silent when operating, although there might be an audible click when
they actually turn the power on or off.

Here's the most suitable-looking example that I found in a quick scan:

http://www.brookstone.com/shop/produ...ct_code=330225

David desJardins