When you sleep you should take off the hearing aid. You can then turn if off to save battery by opening the battery door.
To keep your hearing aid in the best condition you can buy a UV-dry box. This box is designed to sanitize hearing aids and remove moisture and condensation with gentle, dry heat. This is not a replacement for the regular cleaning that is recommended. You can order a dry box at https://www.mdhearingaid.com/en/product/mdhearingaid-uv-clean-and-dry-box/