Introduction to Sleep and Its Disorders

I am honored to have been asked to serve as guest editor for two issues of Seminars in Neurology that focus on sleep disorders. The most important aim is to promote sleep education for a readership commonly confronted with sleep-related problems but rarely well prepared, after most training programs, to address them.

Patients with sleep complaints continue to challenge physicians for several reasons. Given the high prevalence of sleep disorders in the neurology clinic setting and ever-expanding knowledge about sleep disorders, one would have expected a parallel evolution in teaching about sleep disorders in graduate medical education. Unfortunately this has not been the case because there is persistently a lack of sleep education in most medical schools and residency training. Despite the abundance of sleep disorders in neurology clinics, many physicians receive little training about the key tools necessary to obtain a sleep history. The average time spent in teaching about sleep disorders averages ∼2 to 4 hours during the medical school curriculum, which is unlikely to meet the needs of the practicing physician. Physicians are not even taught about sleep and fatigue management in their own lives while they practice in a culture that does not foster adequate sleep. In these two issues devoted to sleep, I hoped to help reinvigorate sleep knowledge and interests among neurologists. The two issues are not meant to serve as a textbook in sleep disorders, but rather to provide an easily-read update about practical approaches to sleep disorders in the neurology practice.

The first of the two issues on sleep disorders covers the more basic aspects of sleep medicine, whereas the second issue is a more in-depth presentation of specific topics. In this issue, I have selected topics that would enable the neurologist, fellow, and resident to develop a conceptual framework of sleep disorders.

I have enlisted the help of outstanding and distinguished authorities in sleep medicine, sometimes in partnership with their more-junior colleagues who specialize in sleep medicine. The author list shows a multisciplinary background that reflects the field itself. While many are neurologists, some are psychiatrists, psychologists, pediatricians, and pulmonologists. This first issue will discuss the major sleep complaints likely to be encountered by a neurologist. Drs. Christopher Sinton and Robert McCarley provide an overview of the basic neuroanatomy and neurophysiology of sleep. Their discussion is an up-to-date account of the mechanism of wakefulness and sleep as a “question of balance.” A general approach to the evaluation of the sleepy patient is provided by Dr. Michael Thorpy. His review comes at a critical time, as the International Classification of Sleep Disorders (ICSD) is currently undergoing critical revisions and updates. Dr. Thropy provides a timely outline of the new classification system at the end of his article. This flows logically into a discussion by Drs. Charles Bae and Nancy Foldvary-Schaefer of the use of sleep studies in patients with neurological diseases. Their discussion covers polysomnography in general and specific sleep montages, and it outlines nicely the indications for sleep monitoring. Next is a description of specific sleep disorders. Drs. Suzanne Lesage and Wayne Hening provide an excellent discussion of restless legs syndrome and periodic limb movements-important neurologic conditions that can be mistaken as psychiatric disorders. A presentation of the neurologic perspective of obstructive sleep apnea is written by Drs. Vivien Abad and Christian Guilleminault; the latter is a pioneer in sleep medicine who discovered much of what we know about sleep apnea. Drs. Jed Black, Stephen Brooks, and Seiji Nishino provide a succinct discussion of narcolepsy and disorders of excessive daytime somnolence. Their clinical and basic science observations have contributed in fundamental ways to the current understanding of the pathophysiology and treatment of narcolepsy. Neurologists are likely to encounter both sleep disorders and several ostensibly-similar spells. A discussion of parasomnias is provided by another group of pioneers, Drs. Mark Mahowald and Carlos Schenck, who first described REM sleep behavior disorder in their classic work from 1986. They coauthored the chapter with Dr. Michel Cramer Bornemann. Due to the unique overlap between epilepsy and sleep, I have included two articles on this subject. The first is an excellent description of nocturnal seizures provided by Dr. Carl Bazil, a clinical epileptologist who developed an interest in the relationship between sleep and seizures. Drs. Bradley Vaughn and O’Neill D’Cruz then outline the linkage between sleep and epilepsy in the second article on the topic. Circadian rhythm abnormalities described by Drs. Kathryn Reid and Phyllis Zee may be the least understood by many clinicians and are often under-diagnosed. Finally, Dr. Timothy Hoban concludes this first issue with a cogent discussion of pediatric sleep disorders.

I would like to conclude by thanking all of the authors for their outstanding contributions. I have had the pleasure of working with many of them as colleagues and friends in this ever-evolving and exciting field. I would like to thank Karen Gowen for her excellent secretarial support. I would also like to thank Dr. Ronald Chervin, Director of the Michael S. Aldrich Sleep Disorders Laboratory, for his creative ideas for topics, outstanding suggestions, and support and encouragement as a mentor and a good friend. I would also like to thank Linda Hagan for her excellent suggestions during numerous discussions of work. I would like to give special thanks to Dr. Karen Roos, Editor in Chief of Seminars in Neurology. I first met Karen after she invited me to attend her course, “Infectious Diseases of the Nervous System,” at the 56th American Academy of Neurology Annual Meeting. I found Karen’s style as a teacher to be among the best I have ever encountered. She is truly an outstanding lecturer, charming and dynamic, warm and personable. Much of the success of Seminars in Neurology as a teaching-styled publication is owed to her.

Finally, on behalf of all the authors, I would like to dedicate the issues on sleep to my teacher and mentor, Dr. Michael S. Aldrich. Dr. Aldrich, who founded the University of Michigan Sleep Disorders Center, was a consummate clinician and clinical researcher. Dr. Aldrich died on July 18, 2000, after a long fight against osteosarcoma. Dr. Aldrich was considered a pioneer neurologist in the relatively young field of sleep medicine. Many of the authors have been privileged to meet and work with him in the past and remember him as a quiet, brilliant, magnificent human being. He continues to serve as role model for many of us who also find themselves fascinated by the scientific frontier defined by the intersection of sleep medicine and neurology.

Michael S. Aldrich, M.D.