All of the advice from Dillinger is good.
Don’t beat yourself up too much for the next few weeks - darkness and cold and Santa all make it difficult to concentrate properly at the moment. You’ll ruin your MH if you start laying into yourself at this time of year.
Getting more rest, getting into a routine, and doing exercise are all good places to start (but I think you’re smart enough to know that already…) It may be a case of being stricter about when you’re working rather than turning off your other interests.