Can you have mania without obvious depression in Bipolar?

Asking this from a relatives point of view. If someone has mania do they always have depression? By depression I mean what the text books describe as depression in Bipolar ie; not wanting to get out of bed, loss of drive etc as after my relative had mania there didn't appear to be any obvious signs of depression. Also, does the depression come immediately after mania like within days or does it happen over a longer period of time. Thanks.