I recommend the Sophie Comfort Sleep Panties, which I bought with my own money.

I highly recommend Sophie's Safe Sleep Panties! I think every woman has worried at least once about whether her period leaked while sleeping. I was so worried the day I bought a new duvet pad that I bought the Safe Sleep Panties—also known as diapers, haha. They are great because they are easy to put on and take off, and they feel softer than regular sanitary pads, so I wear them even when I'm not sleeping. There are various sizes available, but I wanted a looser fit, so I went up one size and it fits comfortably. If you prefer a snug fit, I think buying your regular size would be fine!!