Remember to never leave a bed empty for too long. When heading off for, for example, clean the bed, tuck a broom into it, bristles on the pillow to keep anything negative from settling there.
A blue candle helps protect you while you sleep. Try anointing (or using scented candles) with violet, Rose Geranium, frankincense, bayberry or citronella.
Mirrors are great protection in the bedroom, as it repels negative influences. So put a small one on the headboard, or at least facing the door, and you should stay safe through the night.
Eucalyptus leaves or cinquefoil beneath the pillow, or a knife under the bed will keep you safe through the night.