We wore DD more of less all the time until she was 6 months, and she was put down to bed, in her cot (which was butted up against my bed), at 8pm every night. We had sleep issues like everyone does (her suicide hour was between 6pm and 8-9pm, and she would cry alot between those times whatever we did), but i don't think the sling was a problem. In fact the more she was carried in the day, the better she slept, and my boobs were too big for her to have constant access, so it wasn't that...

Bx