Ensuring that you don’t go to bed while she’s hungry generally tends to be the best way to go. Try filling her kibble bowl just before you go to sleep at night so she has a food source handy. Likewise, consider setting up a bed for her outside your room and locking your door at night to discourage her from eating your dreams.
Alternatively, if you want her to eat your dreams (and, admittedly, this is a good way to supplement her diet), employ a bit of aromatherapy, meditate for at least a half an hour before you go to bed, and try to sleep as relaxed as possible in order to foster good dreams. Keep a dream journal as well to help exercise your subconscious and allow you to dream vividly. The better you get at dreaming (by placing yourself in a relaxed state before sleeping and by chronicling the dreams you can remember), the more you’ll produce good dreams, to the point where you’ll be left with something after your musharna has eaten her fill. Additionally, try to train yourself to daydream during the day to give her something to snack on.
If all else fails, I’ve always felt that dreaming of particularly bizarre things not only encourages creativity but also makes psychics far less inclined to dive into your mindscape. For example, whenever I feel the unmistakable itch of my kadabra (or any psychic, really) attempting to invade my brain, I simply think of this video, and that usually discourages them. View it enough times, and you’ll train yourself to dream about it too.
Best of luck, anonymous!
The Pokédex According to Bill 