Circadian rhythm sleep disorders: lessons from the blind

As totally blind people cannot perceive the light-dark cycle (the major synchroniser of the circadian pacemaker) their circadian rhythms often "free run" on a cycle slightly longer than 24 h. When the free-running sleep propensity rhythm passes out of phase with the desired time for sleep, night-time insomnia and daytime sleepiness result. It has recently been shown that daily melatonin administration can entrain the circadian pacemaker, thereby correcting this burdensome circadian sleep disorder. The primary purpose of this review is to elevate awareness of circadian sleep disorders in totally blind people (especially free-running rhythms) and to provide some guidance for clinical management. An additional goal is to show how research on sleep and circadian rhythms in the totally blind can contribute insights into the scientific understanding of the human circadian system. 2001 Harcourt Publishers Ltd     

Sleep complaints and epilepsy: the role of seizures, antiepileptic drugs and sleep disorders.

Patients with epilepsy commonly complain of daytime sleepiness and poor sleep quality. These problems are frequently attributed to antiepileptic drugs and seizures. Antiepileptic drugs and seizures have effects on sleep architecture often leading to daytime sleepiness. However, sleep symptoms may also be caused by poor sleep hygiene and primary sleep disorders. Primary sleep disorders should be suspected in patients with persistent daytime sleepiness, particularly those on AED monotherapy or with low serum drug concentrations and well-controlled seizures. Treatment of sleep disorders and improved sleep hygiene may improve seizure control and quality of life.     

Pure sleep seizures: risk of seizures while awake.

PURPOSE: To estimate the risk of seizures while awake in pure sleep epilepsies - a long follow-up study. METHODS: Fifty five patients (60% male), with pure sleep epilepsy were followed up for at least ten years. Patients younger than 18 years of age were excluded. The primary endpoint was the occurrence of seizures while awake, after a period of 10 years or longer suffering from pure sleep seizures. RESULTS: The duration of the pure sleep seizures ranged from 10 to 67 years (median 22). The patients had been followed in our Department for a mean of 12 years. Patients' ages ranged from 18 to 88 years (median 50); 44% of patients suffered from apparently generalized seizures. Epilepsy was considered undetermined in 38.2%, focal cryptogenic in 38.2%, and focal symptomatic in 21.8%. There was a single case of idiopathic generalized epilepsy. In the last evaluation, 35 patients were on monotherapy and two were not receiving treatment. Seizure frequency was < 1/year in 65.5%; 1-10/year in 14.5%; > 1/month in 9.1%. Seventeen patients (30.9%) had suffered one or more seizures while awake. Multivariate analysis showed that sudden withdrawal of treatment (p < 0.032) and polytherapy (p < 0.18) were associated with an increased risk of seizures while awake. CONCLUSIONS: In spite of a small number of seizures and good response to monotherapy, a third of the patients studied suffered seizures while awake. The significant risk factors were sudden withdrawal of treatment and polytherapy.     

Primarily generalized seizures are more effective than partial seizures in arousing patients from sleep

The purpose of this study was to determine the characteristics of generalized and partial seizures which awaken patients from sleep, using a retrospective review of intracranial EEG recordings in 8017 electrographic and 7571 clinical seizures in 172 patients undergoing evaluation for epilepsy brain surgery. Seizure onset during sleep followed by awakening occurred in 99% of 308 seizures in 22 patients during daytime naps. Four events consisted of spontaneous awakening followed by the seizure. In contrast electrographic seizures almost never awakened the patient if they were partial in onset (0.02% temporal, 0% frontal), but did so 26% of the time if they were generalized (p < 0.001). Conversely, generalized clinical seizures awakened the patient only 0.3% of the time (p < 0.001) versus 3% for temporal and 6% for frontal lobe. Partial and generalized seizures differ during sleep. Partial seizures do not awaken until they propagate outside the lobe and evolve into a clinical seizure. Generalized seizures when only electrographic, include wake-regulating structures at their onset (presumably thalamus, hypothalamus, brainstem). Our results suggest that rather than sleep transitions being a facilitatory cause of seizures, seizures awaken us from sleep via endogenous stimulation of the brain's sleep/wake structures. This pathway information may be relevant to planning epilepsy brain surgery.     

Cat sleep: A unique first night effect

Longitudinal sleep studies in chronically implanted cats revealed a unique first night effect. Unlike other species, during the first 24 hr of sleep recording, the electroencephalogram and reticular formation multiple unit activity revealed more rapid eye movement sleep occurred than during subsequent 24 hr recording sessions. In addition, higher rapid eye movement to slow wave sleep ratios were observed for the first 24 hr as compared to the following days. An increase in wakefulness and decrease in slow wave sleep occurred on the third recording day as compared to the initial 24 hr period. These data have important implications for studies of variables on the sleep pattern of animals.     

Movement disorders in sleep: guidelines for differentiating epileptic from non-epileptic motor phenomena arising from sleep

Seizures, namely in certain epileptic conditions, may be precipitated by sleep. Nocturnal frontal lobe epilepsy seizures, characterized by bizarre motor behaviour and autonomic activation, appear almost exclusively during sleep. The differential diagnosis between this condition and sleep-related non-epileptic paroxysmal motor phenomena, in particular the parasomnias, is arduous. Moreover, accepted criteria for the diagnosis of nocturnal frontal lobe seizures are lacking and even ictal scalp EEG recording could fail to disclose paroxysmal abnormalities. The clinical and polygraphic features of the different types of seizures in nocturnal frontal lobe epilepsy and of the more common non-epileptic paroxysmal events during sleep are described. The main differentiating features characterizing nocturnal frontal seizures are: onset at any age, several attacks per night at any time during the night, brief duration (s) with stereotyped motor pattern. As video-polysomnographic recordings of the attack, the gold-standard for diagnosis, are expensive and not readily available everywhere, home-made video recordings may be helpful. Further investigations on pathophysiology, genetics and epidemiology are needed to clarify the relationship between epileptic and non-epileptic sleep related paroxysmal phenomena.     

Ambulatory first night sleep effect recording in the elderly

The concept of a first night effect on sleep patterns, specifically in relation to age is a controversial topic in the literature. Our data are obtained during two consecutive 24-h ambulatory home sleep-wake recording in 10 elderly persons with a mean age of 85.5 years. Polysomnographic recordings indicated that a first night effect is present in old age, even using home recording, and that several types of insomnia can be differentiated, stressing that sleep cycle parameters should be taken into account. It is suggested that the first night effect is a 'miniature' replication of a psychophysiological insomnia.     

EEG sleep in young depressives: first and second night effects

The sleep electroencephalogram (EEG) of young, drug-free, recurrently depressed outpatients was analyzed for 2 nights and was compared to age-matched controls using a variety of standard and computerized measures of sleep activity. On the first night, young depressives showed significantly greater difficulty in falling asleep and decreased sleep efficiency. Sleep architecture differences between the young depressives and controls were highlighted by increased percentages of Stage 2 sleep and major decreases in Stages 3 and 4 (delta wave) sleep among the depressives, as indicated by either period analyses or spectral analysis. The greatest differences in delta wave activity during night 1 were found in the first two (non-rapid eye movement (NREM) periods as measured by period analysis (NREM period 1, p less than 0.04; NREM period 2, p less than 0.001--average delta wave count) or by spectral analysis for the first 100 min of sleep (0.5-2.0 Hz). In contrast to the NREM sleep findings, various REM variables, including REM latency did not significantly distinguish the two subject groups for either night 1 or 2. Stepwise discriminant analysis demonstrated that night 1 sleep latency and delta wave counts during the second NREM period correctly classified 100% of all 16 individuals studied. The only differences between the young depressed patients and controls that remained on night 2 were significant reductions in slow-wave sleep as quantified by the computerized methods. Taken together, these findings suggest that the EEG response of young outpatients to the first night's stay in a sleep laboratory may be a useful tool for the diagnosis of depression in this age group. In addition, the use of computerized methods in this study point to an underlying deficit in delta sleep waveforms as being a prominent feature of the sleep of young depressed subjects.     

癫痫患者全夜自然睡眠结构的研究

目的　观察癫痫患者发作间期全夜自然睡眠结构特点 ,并评价其与正常对照组睡眠结构的差异 ;评价发作类型、用药情况及是否记录到发作间电发放对睡眠结构的影响。方法　对 2 0名癫痫患者及 11名对照进行全夜自然睡眠多导监测 ,并结合患者的发作类型、是否记录到发作间电发放 (IIDs)及服用 AEDs的情况进行分组统计分析 ,评价各组患者与正常对照间各睡眠参数的差异。结果　癫痫患者组 ,记录到 IIDs组 ,及该组患者中部分性发作者和未服 AEDs者均较正常对照 TRT、RL 显著延长 (P<0 .0 5)。记录到 IIDs的患者睡眠效率显著下降 (P≤0 .0 5) ,其中部分性发作者入睡后觉醒次数较全身性发作者显著增多 (P<0 .0 5)。部分性发作者较全身性发作者NREM睡眠期转换次数有增高的趋势。不同用药癫痫患者睡眠脑电图较正常对照组睡眠破碎性增加。结论　癫痫患者与正常对照比较 RL延长 ;睡眠破碎性增加 ;记录到 IIDs的患者睡眠效率降低 ;部分性发作患者较全身性发作患者有 NREM期转换次数频繁的趋势 ;记录到 IIDs患者中服用 AEDs的情况对其睡眠结构无显著影响。     

Transition from cortical slow oscillations of sleep to spike-wave seizures

ObjectiveIn cats, spike-wave (SW) seizures have been observed to emerge from cortical slow oscillations (CSOs) and spindles in sleep. We examined a patient’s generalized SW seizures that appeared to emerge from CSOs in sleep.MethodsDense array (256-channel) electroencephalographic (dEEG) data were recorded during long-term monitoring for localizing seizure onset for neurosurgical planning. CSOs were identified on the basis of topographic criteria from dEEG studies of normal human sleep. SW discharges were identified in the surface dEEG and examined with distributed linear inverse neural source estimation.ResultsThis patient’s SW discharges appeared to emerge from a series of CSOs that engaged the left frontal pole. Furthermore, 12 Hz sleep spindles in this patient were often synchronized in time with the CSOs, and in some instances they shared a similar localization over the left frontal pole at the point of seizure onset.ConclusionsThe initial discharges of each seizure engaged both the left frontal pole, which was the primary neural source of this patient’s CSOs, and the left temporal lobe, which seemed critical for the evolution of this patient’s seizures.SignificanceThe correlation of SW seizures with CSOs in animal studies may be observed in humans as well, providing clues to the pathology of arousal regulation in some cases of nocturnal epilepsy.