flax or linseed
Flax or linseed is used to make linen cloth, so if your sheets are linen, you are already set. Although flax is most often used in money and healing spells, there are many medireview references to using flax around the bedside to ward off evil. Eucalyptus is also used primarily for healing, but it is a strong repellent to evil spirits or any form of disease.
Lift up your mattress and sprinkle a handful of flax seeds and eucalyptus leaves underneath. If you are experiencing nightmares add a pinch of coarse salt.
For insomnia add a pinch of chamomile.