Mackenzie is out of nappies for sleeping now - day sleeps last year and night sleeps in Jan this year (whoo!) but she still sleeps on the matress protector which goes over the sheet. I got it from K-mart for about $30. When we stopped wearing nappies for sleeps she just stayed in her knickers and I explained to her why she needed to sit on the toilet before she went to bed and she did great.