Habit is a powerful thing – especially when it comes to sleep. The best evidence suggests that having a stable, consistent sleep schedule – going to bed each night and getting up each morning at the same time – is effective at producing satisfying, efficient sleep.
The first step is to figure out how long your ideal “sleep window” should be – the time you allocate for sleep each night. To do this, keep a sleep diary for a couple of weeks – soon after you wake jot down when you went to bed, how long roughly it took you to fall asleep, how long you were awake for during the night and when you woke for the final time. Then calculate your average total sleep per night, and add 45 minutes to create your ideal allocation of time for sleep each night.
Then choose your ideal, regular bedtime. Based on the length of your sleep window this might be later than you're used to, to wake up at a reasonable hour – but this will help you achieve unbroken, efficient sleep and minimize the time you spend awake during the night.
Finally – the hard part – sticking to it! It will probably not be possible to stick to your new sleep window 7 days a week, but even 4 days a week is likely to make a positive difference. Why not try it for a week or so and see if you notice the difference in how you feel during the day?