Diffusion of essential oils only requires a cereal size bowl and 1 or 2 drops of your favorite essential oil. Just add very hot tap water into a bowl and drop in your essential oil, or blend of 2 or 3 essential oils. The room will delight in the aroma for 1 to 2 hours, a reasonable time to diffuse. More is not better.
The sense of smell is a delicate part of the brain that can easily be overwhelmed. Diffusing for hours will shut down an organ meant for discernment, as well as pleasure. The entire brain suffers, like a stomach constantly fed. If a headache or emotional distress doesn't change or returns after 1 to 2 hours of diffusion, other help should be considered.
Also consider pets children, elderly and visitors whose senses can be easily overwhelmed or harmed by a profusion of scent. For example, Teatree essential oil can be toxic to many pets who will display unusual behavior. Boys under 12 can grow breasts during puberty from smelling or wearing lavender, tarragon or fennel often. Girls under 12 could have a tendency for feminine cancers during maturity. Children may react the opposite of adults to many aromas and become hyperactive , rather than calm. Long diffusion time can tax anyone's kidneys to process the aroma molecules. Generally, it takes 2 hours for the kidneys to filter aroma molecules. Two hours of diffusion takes 4 hours to complete from start to finish. The liver must send the molecular by products to the kidneys in a usable form to prevent toxicity. Anything we smell, touch or eat has a potential for toxicity. Contact me with any concerns or questions.
Live long and enjoy more with common sense aroma lifestyle.