American Society of Hematology disorders of the hematopoietic, hemostatic, and lymphatic systems, and disorders of the interaction between blood and the blood vessel wall. An American hematologist has trained in a subspecialty program approved by the American Board of Internal Medicine or the American Board of Pediatrics, or has acquired a comparable education in the field by alternate means, and is Board Certified (or eligible) in the subspecialty of hematology. Diagnostic expertise of a hematologist A hematologist is expert in the investigation, diagnosis, and management of disorders of the aforementioned organ systems through the use of the medical history, physical findings, specialized clinical laboratory
Classification of sleep disorders occurred a slow confluence of the three systems of classification. Diagnoses of sleep disorders are based on self-assessment questionnaires, clinical interview, physical examination and laboratory procedures. The validity and reliability of various sleep disorders are yet to be proved and need further research within the ever-changing field of "Sleep Medicine". Admittedly, the development of sleep disorder classification remains as much an art as it is a science. The first book on sleep was published in 1830 by Robert MacNish; it described sleeplessness, nightmares, sleepwalking and sleep-talking. Narcolepsy, hypnogogic hallucination, wakefulness and somnolence were mentioned by other authors of the nineteenth