You need to consistently get the amount of hours you need every night at a regular bedtime. You can't really 'catch-up' on sleep if your schedule wildly fluctuates because your body isn't really sure when to release certain hormones to do their job of restoring your health. Under-sleeping one week and then oversleeping the next really isn't the best way to go about this; it's too stressful for your body even if you mentally feel it's ok.
Wind down when the sun goes down and wake up when the sun comes up. Obviously life gets in the way of this very basic yet penultimate rule of thumb, so wind down two hours before you need to go to bed and wake up naturally without using any alarm clocks or other stressful gadgets. Sync up your circadian rhythm and you'll feel the benefits within weeks.