Modern supply units are divided into two or more sections, each governed by a residual current device which, if tripped, will shut down each section in turn. It sounds like this may be what happens in your case - the cause will be some device/equipment which has what is referred to as a "leak". This can be almost anything but it is well known that certain fridges, freezers and large TVs can cause this. The way to check is to unplug one item at a time and once the tripping stops re-plug the item in again and see if the pattern starts again.
Alternatively, if only one circuit breaker is being tripped then that is likely an overload of some sort, perhaps a short (maybe intermittent) in some item, and that could be almost anything on that circuit, including a switched socket (I have had at least two examples).