I think it's really important to control hypomanias cos in my experience unless they are managed well they inevitably end in a depression. By not letting it get to high for too long and stopping myself from doing things I regret later I usually manage to make a soft landing and not get depressed. I guess if you don't get depressed and don't do things that you regret then it doesn't matter so much but there is a theory that bipolar gets worse untreated so that is another reason for controlling the hypomanias.

As to your original question. Sleep is the big one for me. I take sleeping tablets and make myself stay in bed and do nothing even if I can't sleep. Mini meditations help as well to slow down my thoughts - set a timer for 1-2 mins and focus on one thought for that time. Try to extend the time out to 5 mins. I find gentle exercise like walking helps best cos if I push to hard the adrenalin can make things worse. I also postpone big decisions and purchasing decisions till after the hypomania has subsided.

I know you asked for non med strategies but I also have meds that I take only if I get hypomanic.