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 neurologist treats brain and nervous system disorders that may contribute to sleep problems.  An otolaryngologist treats ear, nose, and throat conditions. This doctor may evaluate snoring and other breathing problems associated with sleep disorders.
Sleep specialists typically have a specialty in one field. Behavioral sleep medicine (BSM) specialists, for example, have extensive training in treating chronic insomnia. The AASM keeps an updated list of BSM specialists on their website, although there are only about a hundred certified throughout the country.