You are getting sleepy. Very sleepy. You will forget everything you read in this article.

Hypnosis has become a common medical tool, used to reduce pain, help people stop smoking and cure them of phobias.

But scientists have long argued about whether the hypnotic “trance” is a separate neurophysiological state or simply a product of a hypnotized person’s expectations.

A study published on Thursday by Stanford researchers offers some evidence for the first explanation, finding that some parts of the brain function differently under hypnosis than during normal consciousness.

The study was conducted with functional magnetic resonance imaging, a scanning method that measures blood flow in the brain. It found changes in activity in brain areas that are thought to be involved in focused attention, the monitoring and control of the body’s functioning, and the awareness and evaluation of a person’s internal and external environments.