Chapter 31

Sleep disorders

ULRICH VODERHOLZER1* AND CHRISTIAN GUILLEMINAULT2

1Schoen Clinic Roseneck, Prien and Department of Psychiatry and Psychotherapy, University of Freiburg Medical Center,Freiburg, Germany

2Stanford University Sleep Disorders Program, Stanford, CA, USA

BASICSOF SLEEPRESEARCH

Modern sleep research began with the discovery ofrapid eye movement (REM) sleep by Aserinsky andKleitman in 1953. Over the following years, polysom-nography was developed and the physiological sleepprofile of healthy subjects was elucidated. Polysomno-graphy consists of the simultaneous recording of elec-troencephalogram (EEG), electro-oculogram (EOG)and electromyogram (EMG). Furthermore, modernpolysomnography includes cardiorespiratory parame-ters, such as electrocardiogram (ECG), respirationfrequency, oxygen saturation, snoring, and leg move-ments. The sleep EEG is routinely scored according tothe criteria described by Rechtschaffen and Kales(1968) and more recently by the American Academyof Sleep Medicine (Iber et al., 2007). Every 30-secondepoch of the recording is classified as a certain sleepstage and the nocturnal sleep profile is compiled(Fig. 31.1) on the basis of these 30-second epochs. In ad-dition to an all-night polysomnogram, the MultipleSleep Latency Test (MSLT) or the Maintenance ofWakefulness Test (MWT) may also be administered,predominantly for the diagnosis of hypersomnia or nar-colepsy (Carskadon et al., 1986). In the MSLT, the sleepEEG is monitored at five defined time points, 09.00,11.00, 13.00, 15.00, and 17.00 hours for a 20-minute pe-riod, lying in bed with eyes closed in a dark room, in or-der to test the ability to fall asleep. The MWT, the onlytest that has medicolegal validity in some countries, isperformed four times during the day, at 09.00, 11.00,14.00, and 16.00 hours. Each test lasts 40 minutes andthe subject sits in a comfortable armchair in a relaxedposition in the dark and his or her ability to stay awakeis assessed (Philip et al., 2008).

NORMAL SLEEP

Sleep consists of two different states, REM and non-REM (NREM) sleep. REM sleep is defined by thepresence of an EEG pattern of low-voltage fast wavesassociated with the occurrence of REMs, isolated orin bursts, along with postural relaxation, i.e., muscleatonia. The muscle atonia is interrupted by bursts ofmuscle tone, leading, at times, to jerking movements.These twitches and bursts of eye movements are calledphasic events, occurring on a background of tonic mus-cle inhibition, and define phasic REM sleep, in contrastto tonic REM sleep, where the scored epoch consistsonly of the REM sleep EEG and muscle atonia. Electro-physiological studies performed on cats have shown thatthe phasic events are associated with bursts of wavesthat appear simultaneously in the pons, lateral genicu-late, and occipital lobe (Jouvet, 1972; Laurent et al.,1974). These waves are called pontogeniculo-occipital(PGO) spikes or waves and their presence dissociatesphasic from tonic REM sleep in mammals. The term“REM sleep” is synonymous with “desynchronized(D) sleep,” “dream sleep,” “paradoxical sleep,” and,in infants, “active sleep.”

NREM sleep, also called “synchronized sleep,” and,in infants, “quiet sleep,” has been subdivided into foursleep stages. Stage 1 (N1) is seen at sleep onset and is de-fined by low voltage and mixed frequency (2–7 Hz),with an absence of REM and presence of muscle tone.Vertex sharp waves may be seen, and slow eye move-ments are often present. Stage 2 (N2) is reached when12–14-Hz sleep spindles and/or K complexes appearagainst a background activity of relatively low-voltagemixed EEG frequencies. Stage 3 is scored when a mod-erate amount (20–50% of an epoch) of high-amplitude

*

Correspondence to: Professor Ulrich Voderholzer, Medical Director, Schoen Clinic Roseneck, Am Roseneck 6, 83209 Prien,

Germany. Tel: 08051 683510, E-mail: UVoderholzer@Schoen-Kliniken.de

Handbook of Clinical Neurology, Vol. 106 (3rd series)Neurobiology of Psychiatric DisordersT.E Schlaepfer and C.B. Nemeroff, Editors# 2012 Elsevier B.V. All rights reserved