most people (myself included) listen to music or relaxation / mindfulness when sleeping which blocks out the voices of alters and at the same time keeps dissociatives grounded.

there are many great radio, netflix, internet, even blue ray players, laptops, computers and cell phones have aps and channels for this kind of thing and most are free. though netflix does have a monthly access fee.

walmart, target and other department stores also sell MP3 players where you can download or upload the music/ mindfulness/ relaxation sounds you enjoy.

All I do is turn on my blue ray, find the mindfulness/ relaxation sound I want to listen to, and off to sleep I would go, worked even when I wasnt integrated.