Waking up at night hungry

I started my weight loss journey about 5 weeks ago when husband went on a business trip. Lost 10lbs pretty quickly, now am waiting for more lbs to go away (and never come back :-)

Anyway, when I first started I didn't have this problem but in the past week, I had a few evenings when I was really hungry (after having eaten all my calories for the day - I am at 1220 calories/day not counting my exercise calories which I will eat back, at least partially) and there have now also been 3 nights that I woke up with a growling stomach.

I eat very healthy during the day - chicken/fish, peanut butter, veggies or salad, fruit, some carbs (whole wheat bread etc.), low-fat dairy products (yogurt..), good fats (avocado, olive oil). I drink a good amount, too, although not solely water (because at this point, it makes me gag but I am working on getting to "just plain water") - I drink extremely diluted grapefruit juice (essentially water with a bit of grapefruit juice), some black tea with lemon and a bit of sugar and occasionally a latte without sugar.

If I wake up, I try to ignore my stomach and go back to sleep. If that doesn't help, I get up. I have eaten: strawberries, carrots with peanut butter, bread, yogurt at night. And I drink some of my diluted water with grapefruit juice.

But seriously, what is the problem? Why do I wake up hungry, now after I was fine the first few weeks??

And any recommendations on what to do during the day to stop this, and also what to do at night when waking up?

Thanks!