Sleeping through the night - engorged breasts

Hi,

I know this is a luxury problem, but my baby sleeps through the night (from midnight till 6 in the morning) at 3.5w. My breasts are not a fan of his new sleeping patern however and hurt like hell when he finally wakes up. I then spend quite some time massaging the clogged ducts out and even then it still hurts. When he slept 4h on end, I used to wake up from the pain and would be able to pump the pain away then, but I seem to be sleeping through it now and then wake up in a lot of pain. I massage and pump and massage some more but it seems a bit stuck now and I am scared to end up with mastitis (I barely prevented it last time). How do I give my brain the sign to stop producing so much milk at night? Ah and not to worry, my son eats more than enough and cluster feeds during the day.