In the primary repression phase, 'it is highly probable that the immediate precipitating causes of primal repressions are quantitative factors such as...the earliest outbreaks of anxiety, which are of a very intense kind'.
1 A psychiatrist treats mood disorders, such as anxiety and depression, which can contribute to sleep problems. Psychiatrists may conduct therapy and prescribe medication to relieve symptoms.  A psychologist provides psychotherapy to treat mood disorders that can interfere with sleep.
A neurologist is a physician who specializes in disorders of the brain, particularly the nervous system. A competent neurologist treats patients who suffer from a wide range of conditions, including dementia, epilepsy, brain tumors, amnesia, and migraine disorder.