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.
Neurologists. A patient with insomnia may also be referred to a neurologist. A neurologist is a physician with in-depth training in nervous systems disorders. An imbalance in brain chemistry can bring on a host of negative symptoms that include insomnia. Neurologists also treat restless leg syndrome, a common cause of insomnia.