NREM sleep is divided into 4 stages. Stages 1 and 2 are characterized by low arousal thresholds and are considered light sleep. Stages 3 and 4 are characterized by high arousal thresholds and are considered deep or “slow wave” sleep. All 4 of these stages can be differentiated by electroencephalography (EEG). Stage 1 is marked by low voltage, mixed frequency EEG. Stage 2 is marked by the presence of K complexes and sleep spindles on EEG recordings. Both stages 3 and 4 are marked by delta waves, which have a voltage of 75 microvolts or more and a frequency range of 0.5 to 4 hertz, but differ in composition. Stage 3 is defined as sleep consisting of 20-50% delta waves and stage 4 as sleep consisting of more than 50% delta waves. REM sleep is characterized by minimal movement, low muscle tone, activation of cortical activity, and rapid eye movements accompanied by vivid dreams. [Text: Comella, p. 18-B; Pace-Schott, p. 600. Figure: Pace-Schott, p. 600] Comella CL, Walters AS, Hening WA. Sleep and wakefulness. In: Goetz CG, Pappert EJ, eds. Textbook of Clinical Neurology . Philadelphia: WB Saunders Company; 1999:18-27. Pace-Schott EF, Hobson JA. The neurobiology of sleep: genetics, cellular physiology and subcortical networks. Nat Rev Neurosci . 2002;3:591-605. Scammell TE. The regulation of sleep and circadian rhythms. Sleep Med Alert. 2004;8:1-6.
Inv sleep 2012
Investigations of sleep disorders BY Dr.Jaidaa Mekky Lecturer of Neuropsychiatry Sleep Medicine ConsultantMember of the American Academy of Neurology Member of the American Academy of Sleep Medicine Faculty of Medicine Alexandria University
Background• One-half to one-third of life asleep• Sleep medicine relatively new field• Sleep is a co-morbidity in a long list of diseases• It was mentioned in the holy Quran 9 times, describing the sleep fnctions and stages وقال إن أبقراط قال: إذا كان النوم فى المراض المزمنة يس ّب وجعً، فذلك ا ب . من علمات الموت
Milestones• 1837 – Dickens – describes overweight/hypersomnolent boy in the Posthumous Papers of the Pickwick Club (term “pickwickian” used by Osler)• 1875 – Caton – EEG in dogs• 1928 – Berger – Human EEG alpha waves• 1937 – Loomis – EEG Sleep stages described
Milestones• 1953 – Aserinsky & Kleitman – REM sleep• 1970s – Polysomnography• 1972 – Guilleminault – coins term OSA• 1990 – International Classification of Sleep Disorders
Sleep Physiology• What is Sleep? – “a reversible behavioral state of perceptual disengagement from and unresponsiveness to the environment”• 75% in Non-REM sleep• 25% REM sleep – muscle atonia, autonomic activation
A major input to the relay and reticular nuclei of the thalamus (yellow pathway) originates from cholinergic (ACh) cellgroups in the upper pons, the pedunculopontine (PPT) and laterodorsal tegmental nuclei (LDT). These inputs facilitatethalamocortical transmission. A second pathway (red) activates the cerebral cortex to facilitate the processing of inputsfrom the thalamus. This arises from neurons in the monoaminergic cell groups, including the tuberomammillary nucleus(TMN) containing histamine (His), the A10 cell group containing dopamine (DA), the dorsal and median raphe nucleicontaining serotonin (5-HT), and the locus coeruleus (LC) containing noradrenaline (NA). This pathway also receivescontributions from peptidergic neurons in the lateral hypothalamus (LHA) containing orexin (ORX) or melanin-concentrating hormone (MCH), and from basal forebrain (BF) neurons that contain γ-aminobutyric acid (GABA) orACh. Note that all of these ascending pathways traverse the region at the junction of the brainstem and forebrain wherevon Economo noted that lesions caused profound sleepiness.
S taging M ove m e nt T im e Awak e RE M S tage 1 S tage 2 S tage 3 S tage 4 11 Õ 12 ã 01 ã 02 ã 03 ã 04 ã 05 ã 06 ãPos ition Le ft R ight S upine P rone U prightPL MS With Arou s al W/O Arou s al Respiratory E vents Mixe d Apne a O bs tructive Apne a C e ntral Apne a Hypopne a
The main data presented in PSG are:• 1) Total sleep time, wake time, total recording time;• 2) Sleep efficiency (total sleep time/total recording time);• 3) Latency for sleep onset, latency for REM sleep and other sleep stages.• 4) Duration (in minutes) and proportion of total-sleep-time sleep stages (5) Frequency of apneas and hypopneas per hour of sleep• 6) Saturation values and events of oxyhemoglobin desaturation• 7) Total number and index of periodic lower limb movements per hour of sleep.• 8) Total number and index of micro-arousals per hour of sleep and their relationship with breathing events or lower limb movements;• 9)Esophageal ph anormalities• 10)Penile tumecence
Actigraphy• Cost efficient• Records motor movements• Aallows estimates for several days, avoiding the sampling error of NPSG• It gives an idea about TST,SL, Nocturnal arousals• It is superior to sleep log
Uses:• Used in assessment of Insomnia• Useful in children and old age• Circadian rhythm disorders• Epidemiologic sleep studiesLimitations:• It is not standardized yet for diagnosing PLMS,SDB or RBD.