Polysomnographic effects of hypnotic drugs. A review

Rhythmic movement disorder and cyclic alternating pattern during sleep: A video-polysomnographic study in a 9-year-old boy

We report on polysomnographic findings in a 9-year-old boy affected by rhythmic movement disorder. The subject's rhythmic movements were found to be intimately linked to unstable nonrapid eye movement N-REM sleep, as shown by their close association with the A phases of the cyclic alternating pattern. We examine the complex interactions between arousal mechanisms and rhythmic movements occurring during sleep.

Is insomnia a neurophysiological disorder? The role of sleep EEG microstructure

Unlike other sleep disorders, such as sleep-related breathing disorders and periodic limb movement (PLM), the nature and severity of which are quantified by specific respiratory and motor indexes, no apparent organ dysfunction underlies several cases of insomnia (in particular primary insomnia), which can be objectively diagnosed only through the structural alterations of sleep. Polysomnography (PSG) investigation indicates that insomnia is the outcome of a neurophysiological disturbance that impairs the regulatory mechanisms of sleep control, including sleep duration, intensity, continuity and stability. In particular, analysis of sleep microstructure has permitted to establish that etiologic factors of different nature (including depressive disorders) exert a common destabilizing action on sleep, which is reflected in an increase of cyclic alternating pattern (CAP) rate. These premises allow us to attribute a more objective identity to insomnia, which risks otherwise to be considered as an unexplainable mental complaint. In conclusion, PSG remains the "gold standard" for measuring sleep, and especially insomnia.

The nature of arousal in sleep

The role of arousals in sleep is gaining interest among both basic researchers and clinicians. In the last 20 years increasing evidence shows that arousals are deeply involved in the pathophysiology of sleep disorders. The nature of arousals in sleep is still a matter of debate. According to the conceptual framework of the American Sleep Disorders Association criteria, arousals are a marker of sleep disruption representing a detrimental and harmful feature for sleep. In contrast, our view indicates arousals as elements weaved into the texture of sleep taking part in the regulation of the sleep process. In addition, the concept of micro-arousal (MA) has been extended, incorporating, besides the classical low-voltage fast-rhythm electroencephalographic (EEG) arousals, high-amplitude EEG bursts, be they like delta-like or K-complexes, which reflects a special kind of arousal process, mobilizing parallely antiarousal swings. In physiologic conditions, the slow and fast MA are not randomly scattered but appear structurally distributed within sleep representing state-specific arousal responses. MA preceded by slow waves occurs more frequently across the descending part of sleep cycles and in the first cycles, while the traditional fast type of arousals across the ascending slope of cycles prevails during the last third of sleep. The uniform arousal characteristics of these two types of MAs is supported by the finding that different MAs are associated with an increasing magnitude of vegetative activation ranging hierarchically from the weaker slow EEG types (coupled with mild autonomic activation) to the stronger rapid EEG types (coupled with a vigorous autonomic activation). Finally, it has been ascertained that MA are not isolated events but are basically endowed with a periodic nature expressed in non-rapid eye movement (NREM) sleep by the cyclic alternating pattern (CAP). Understanding the role of arousals and CAP and the relationship between physiologic and pathologic MA can shed light on the adaptive properties of the sleeping brain and provide insight into the pathomechanisms of sleep disturbances. Functional significance of arousal in sleep, and particularly in NREM sleep, is to ensure the reversibility of sleep, without which it would be identical to coma. Arousals may connect the sleeper with the surrounding world maintaining the selection of relevant incoming information and adapting the organism to the dangers and demands of the outer world. In this dynamic perspective, ongoing phasic events carry on the one hand arousal influences and on the other elements of information processing. The other function of arousals is tailoring the more or less stereotyped endogenously determined sleep process driven by chemical influences according to internal and external demands. In this perspective, arousals shape the individual course of night sleep as a variation of the sleep program.

CAP variables and arousals as sleep electroencephalogram markers for primary insomnia

OBJECTIVE

Polysomnographic (PSG) measures consistently reflect poor sleep quality and effective treatment in insomniac patients.

METHODS

The PSG findings of 47 patients (18 M and 29 F, 42.5+/-10 years) meeting the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria for a diagnosis of primary insomnia were compared with those of 25 age- and gender-balanced healthy subjects (controls) without sleep complaints. After one adaptation night to the sleep lab, each patient underwent two randomized double-blind PSG recordings. Twenty-four patients followed a placebo-drug sequence and 23 a drug-placebo succession. Active treatment consisted of widely used hypnotic drugs, i.e. zolpidem, triazolam, zopiclone, brotizolam. Conventional PSG measures, electroencephalogram (EEG) arousals and CAP variables (including phase A subtypes) were quantified and statistically analyzed.

RESULTS

Compared to controls, insomniac patients under placebo showed a significant increase of CAP rate, subtypes A1 and A2, EEG arousals, nocturnal wakefulness and stage 1, associated with reduced values of total sleep time and slow wave sleep (stages 3 and 4). In insomniac patients, sleep quality was significantly improved by hypnotic treatment. Compared to placebo, active medication significantly reduced CAP rate, subtypes A1 and A2, but had only marginal effects on subtypes A3 and on EEG arousals. Under hypnotic treatment total sleep time, nocturnal awakenings, stage 1 and slow wave sleep recuperated normal values. The most significant correlation between sleep quality and PSG variables was found for CAP rate (P<0.0001).

CONCLUSIONS

PSG investigation extended to CAP variables and EEG arousals can be an important procedure for the diagnosis of primary insomnia and evaluation of treatment efficacy.

Problems with sleep: what should the doctor do?

Complaints of poor sleep are frequent. The physician's assessment should seek to diagnose the social, medical, and psychiatric etiologies of insomnia and to treat the identified causative conditions. Management must match the specific pathology and type of sleep problem.

New drugs for insomnia: comparative tolerability of zopiclone, zolpidem and zaleplon

Insomnia affects 30-35% of people living in developed countries. The impact of insomnia on daytime functioning and its relationship with medical and psychiatric illnesses necessitate early treatment to prevent insomnia becoming persistent and to avoid the development of complications. However, pharmacological strategies must achieve a balance between sedative and adverse effects. In the last 30 years, benzodiazepines have been the preferred drugs for the treatment of insomnia. Benzodiazepines act nonselectively at two central receptor sites, named omega(1) and omega(2), which are located in different areas of the CNS. The sedative action of benzodiazepines is related to omega(1) receptors, whereas omega(2) receptors are responsible for their effects on memory and cognitive functioning. According to their pharmacokinetic profile, benzodiazepines can be classified into three groups: short half-life (<3 hours), medium half-life (8-24 hours) and long half-life (>24 hours). The newer non-benzodiazepine agents zopiclone, zolpidem and zaleplon have a hypnosedative action comparable with that of benzodiazepines, but they display specific pharmacokinetic and pharmacodynamic properties. These three 'Z' agents all share a short plasma half-life and limited duration of action. In addition, these agents are selective compounds that interact preferentially with omega(1) receptors (sedative effect), whereas benzodiazepines also interact with omega(2) receptors (adverse effects on cognitive performance and memory). Zaleplon is characterised by an ultrashort half-life (approximately 1 hour). Zolpidem and zopiclone have longer half-lives (approximately 2.4 and 5 hours, respectively). These properties, together with the low risk of residual effect, may explain the limited negative influences of these agents on daytime performance. Psychomotor tasks and memory capacities appear to be better preserved by non-benzodiazepine agents than by benzodiazepines. When present, cognitive deficits almost exclusively coincide with the peak plasma concentration. In particular, impairment can emerge in the first hours after drug administration, whereas psychomotor and memory tests carried out 7-8 hours later (i.e. in the morning) generally show no relevant alterations. As with benzodiazepines, the three 'Z' non-benzodiazepine agents should be used for a limited period, even in chronic relapsing conditions. Further evaluation is needed of the safety of hypnosedative medications in the long-term management of insomnia.

Consensus on Drug Treatment, Definition and Diagnosis for Insomnia

Thirty-four experts and a literature supervisor got together in order to reach a 'consensus' regarding the definition, diagnosis and pharmacological treatment of insomnia. Insomnia is a subjective perception of dissatisfaction with the amount and/or quality of sleep. It includes difficulty in initiating or maintaining sleep or early awakening with inability to fall asleep again. It is associated with complaints of non-restorative sleep and dysfunction of diurnal alertness, energy, cognitive function, behaviour or emotional state, with a decrease in quality of life. The diagnosis is based on clinical and sleep history, physical examination and additional tests, although polysomnography is not routinely indicated. Therapy should include treatment of the underlying causes, cognitive and behavioural measures and drug treatment. Hypnotic therapy can be prescribed from the onset of insomnia and non-benzodiazepine selective agonists of the GABA-A receptor complex are the drugs of first choice. It is recommended that hypnotic treatment be maintained in cases where withdrawal impairs the patient's quality of life and when all other therapeutic measures have failed. Experience suggests that intermittent treatment is better than continuous therapy. The available data do not confirm safety of hypnotics in pregnancy, lactation and childhood insomnia. Benzodiazepines are not indicated in decompensated chronic pulmonary disease but no significant adverse effects on respiratory function have been reported with zolpidem and zopiclone in stable mild to moderate chronic obstructive pulmonary disease and in treated obstructive sleep apnoea syndrome. Data for zaleplon are inconclusive. If the patient recovers subjective control over the sleep process, gradual discontinuation of hypnotic treatment can be considered.

Tolerability of hypnosedatives in older patients

Sleep disturbances are common and prevalence rates increase with age. Especially in the elderly, somatic diseases and medications with adverse effects relating to sleep are frequent reasons for disturbed and nonrefreshing sleep. It should be emphasised that these reasons must be excluded before symptomatic therapy is started. In some cases the use of hypnosedatives may be included as part of the treatment of a somatic disease and may cause sleep disturbances. Pharmacotherapy is one of the main approaches in the management of primary insomnia and should be part of a broader treatment strategy including nonpharmacological methods. This article focuses on the tolerability of frequently prescribed hypnosedatives in the elderly with primary insomnia and addresses the primary care physician. In general, recommendations for the pharmacotherapy of insomnia in elderly patients include using a reduced dosage. For some substances (e.g. zolpidem, zopiclone, zaleplon, temazepam and triazolam) the recommended dosage is half that recommended for younger patients. The properties of the selected hypnosedative should be taken into consideration and matched with the type of sleep disturbance experienced by the patient. Ultrashort-acting drugs may be useful when initiating sleep is the main problem, whereas short- and intermediate-acting substances are recommended for maintaining sleep. Possible interactions with pre-existing medication must also be taken into consideration. Some agents such as antipsychotics, antidepressants, melatonin and herbal agents may be used in specific indications. However, only a few of these substances have proven tolerability in the elderly and further investigations are recommended.

Spike-wave discharge and the microstructure of sleep-wake continuum in idiopathic generalised epilepsy

This review summarises all the evidences about the influence of different vigilance states on the occurrence of spike wave discharge (SWD) in idiopathic generalised epilepsy (IGE) patients. Numerous converging observations showed that full REM-sleep and alert wakefulness exert strong inhibition. A critical zone of vigilance which is a transitional state between waking and non-REM (NREM) sleep, and NREM sleep and REM sleep, has a promoting effect on the absence type spike wave discharge. Spike wave discharges are associated with phasic arousals without awakening and are attached to oscillation son the microstructural level of sleep, perpetuated by cyclic arousal events known as 'cyclic alternating pattern' (CAP), especially within the critical zone, but also along the whole sleep process. More specifically SWD seems to be attached to the 'A-phase' of CAP which is a reactive one and reflects synchronised NREM sleep EEG elements, like K-complexes, spindles and delta groups. The more slow wave elements are found in phase A--like in subtype A1--the more the coincidence with SWD occurs, and the more it is characterised by fast rhythms--as in subtype A2 and A3--the less the association with SWD could be observed. Since subtype A1 is associated with the first sleep cycle and with the descending branches of cycles, it is concluded that SWD appear in those dynamic moments of vigilance level oscillations which were characterised by strong sleep-like answers to arousal influences in high sleep pressure periods of sleep cyclicity. These data harmonize with another line of evidence suggesting that SWD represent the epileptic variant of the complex thalamocortical system function which is the substrate of NREM sleep EEG phenomena. In idiopathic generalised epilepsy there is a growing body of evidence that--as it was assumed by Gloor--spindles transform to SWD pattern. These data explain why those dynamic changes which evoke sleep responses are promoting for the occurrence of SWD. Adapting these data we offer a new interpretation to explain the strong activation effect of sleep deprivation in this kind of epilepsy. We assume that it is mainly due to the forced vigilance level oscillations, especially in morning, when elevated sleep pressure and circadian wake promoting forces, representing opposite tendencies, increase the amount of oscillations.

A double-blind comparative study of zolpidem versus zopiclone in the treatment of chronic primary insomnia

Zolpidem (10 mg/day) and zopiclone (7.5 mg/day), administered at night, were compared in a 14-day, double-blind, equivalence trial on 479 chronic primary insomniacs (zolpidem, 231; zopiclone, 248) throughout Japan, with a 1-week follow-up to assess rebound. The primary endpoint was the investigators' rating of global improvement of sleep disorders. A total of 32 patients in the zolpidem group (13.9%) and 45 patients in the zopiclone group (18.1%) withdrew from the study before the end of the treatment. In the zolpidem group, 67.9% (142/209) of patients were rated at least 'moderately improved' versus 61.6% (135/219) with zopiclone, zolpidem being at least as effective as zopiclone (90% confidence interval: -1.7, 14.3). With zolpidem, sleep onset latency improved in significantly more patients (85.8% versus 77.5%) and significantly fewer patients showed aggravated sleep onset latency relative to baseline at follow-up (4.5% versus 15.4%). Significantly fewer patients receiving zolpidem experienced drug-related adverse events (31.3% versus 45.3%), with bitter taste representing 5.8% (six of 104) of such complaints with zolpidem compared with 39.9% (69/173) with zopiclone. In conclusion, zolpidem was at least as effective as zopiclone, showed significantly less rebound on discontinuation and was better tolerated.

Insomnia in the context of cancer: a review of a neglected problem

This article reviews the evidence on the diagnosis, epidemiology, etiology, and treatment of insomnia in the context of cancer and proposes several areas for future research. Clinical and diagnostic features of insomnia are described and prevalence estimates of insomnia complaints in cancer patients are summarized. Then, potential etiologic factors (ie, predisposing, precipitating, and perpetuating factors) and consequences of insomnia (ie, psychologic, behavioral, and health impact) in the context of cancer are discussed. Finally, pharmacologic and psychologic treatments previously shown effective to treat insomnia in healthy individuals are discussed as valuable treatment options for cancer patients as well. Because long-term use of hypnotic medications is associated with some risks (eg, dependence), it is argued that psychologic interventions (eg, stimulus control, sleep restriction, cognitive therapy) are the treatment of choice for sleep disturbances in the context of cancer, especially when it has reached a chronic course. However, the efficacy of these treatments has yet to be verified specifically in cancer patients.

Insomnia in Adults

Insomnia is a prevalent condition, existing as both a symptom and a syndrome, and is associated with significant impairments of daytime functioning, reduced quality of life, and increased risk of depression. When insomnia is secondary to a psychiatric, medical, or another sleep disorder, treatment should focus initially on the underlying condition. For acute and situational insomnia, treatment should address the precipitating factors when possible, but in certain circumstances (eg, stressful events, travel, or jet lag), a hypnotic medication is necessary to alleviate sleep difficulties. Benzodiazepine-receptor agents are the treatment of choice among the pharmacologic options. For chronic and primary insomnia, behavior treatment should represent the main intervention, with hypnotic medications serving as an adjunct. Behavior and pharmacologic treatments can be effectively combined in order to take advantage of the faster results obtained from medication administration, and the longer-lasting benefits associated with behavior interventions. For recurrent insomnia, the use of intermittent medication can be very useful to prevent or minimize continued sleep difficulties.

Non-benzodiazepines for the treatment of insomnia

Benzodiazepine hypnotics, the mainstay of pharmacological treatment for insomnia, have been associated with altered sleep architecture, psychomotor and memory impairment, rebound insomnia, withdrawal effects, tolerance, dependence, abuse potential and respiratory depression. Non-benzodiazepines, such as zolpidem, zopiclone and zaleplon, demonstrate hypnotic efficacy similar to that of benzodiazepines along with excellent safety profiles. Non-benzodiazepines generally cause less disruption of normal sleep architecture than benzodiazepines. Psychomotor and memory impairment may be less problematic with non-benzodiazepines, especially when compared to longer-acting benzodiazepines. Rebound insomnia and withdrawal symptoms occur infrequently upon discontinuation of non-benzodiazepines and may be less common and milder than those seen upon discontinuation of some benzodiazepines. For the long-term treatment of insomnia, which is generally not recommended, zolpidem and zopiclone are particularly good options because they do not develop tolerance rapidly and have a low abuse potential. Limited data indicate that zaleplon has low tolerance and abuse potential, although further experience is needed to determine its long-term efficacy and safety profile. Since non-benzodiazepines produce minimal respiratory depression, they may be safer than benzodiazepines in patients with respiratory disorders. The choice of which hypnotic to use should be based on the patient's primary sleep complaint, health history, adverse effects and cost.

New trends in insomnia management

Pharmacological management of insomnia is continually evolving. The introduction of non-benzodiazepine benzodiazepine receptor agonist hypnotics provides an opportunity to understand different patterns of pharmacological activity with mechanistic differences in receptor activity. The impact of insomnia on daytime functioning and long-term health and socioeconomic status has been recognized. Epidemiological studies indicate that insomnia is associated with increased absenteeism and healthcare costs (although the latter appear to be partly attributable to comorbid depression). It will thus be important to determine whether hypnotics, in addition to their effects on sleep, provide other benefits for the patient that are related to these parameters. The successful resolution of this issue will require the adoption of additional outcome measures, such as effects on quality of life and healthcare costs. Recognition that long-term hypnotic use is widespread among insomniacs has prompted proposals for alternative prescribing patterns. Although certain hypnotics appear to be free of tolerance on prolonged use, caution is required in the long-term use of any hypnotic because of the lack of systematic data on chronic efficacy and safety. Therefore, alternative administration schedules (e.g. intermittent and 'as required') are being investigated. These may have very different consequences in terms of abuse liability and patients' perceptions of efficacy, and thus permit a more effective and appropriate use of this drug class.

Origin and Significance of the Cyclic Alternating Pattern (CAP). REVIEW ARTICLE

This article reviews the 15 years of studies conducted on the cyclic alternating pattern (CAP), the electro- encephalogram (EEG) marker of arousal instability during sleep. Starting from the limits and drawbacks of conventional sleep parameters (macrostructure), investigation of the underground world (microstructure) is extensively carried out with particular attention to K-complexes and other arousal-related phasic events of non-rapid eye movement (NREM) sleep. The continuity between conventional and non-conventional arousals is stressed in the light of autonomic function and motor activity evidence. The similarities and differences between CAP and arousals are thoroughly illustrated as well as the putative biological bases of these phenomena. The oscillatory nature of CAP, the involvement of CAP in the modulation of EEG synchrony, the sleep-maintenance properties of CAP in response to arousing stimuli, the clinical applications of CAP parameters and the promising availability of automatic scoring systems are highlighted.

The safety and tolerability of zolpidem--an update

Zolpidem belongs to a new class of hypnotic agents, chemically distinct from the pre-existing ones, and has a unique neuropharmacological profile. It induces sedative/hypnotic effects in rodents at doses much lower than those for anticonvulsant and myorelaxant activities. Clinically, zolpidem is indicated for the short term treatment of insomnia. It has a short half-life (2.4h), with no active metabolite, and does not accumulate during repeated administration. The pharmacokinetic profile associated with the absence of active metabolites is consistent with the short duration of action and absence of residual effects that have been observed. Polysomnographic experience indicates that zolpidem induces a sleep pattern which is similar to that of physiological sleep, and which produces either no or only minimal effects on sleep architecture after abrupt discontinuation. Aspects of the general safety of zolpidem have been studied in data obtained from healthy volunteers and patients, both adult and elderly, during its clinical development and in post-marketing experience. Zolpidem appears to be well-tolerated in adults and in the elderly, when administered in accordance with prescribing instructions. The available data indicate that, in these circumstances, the risk of abuse or dependence is minimal.

Comparison of continuous versus intermittent administration of zolpidem in chronic insomniacs: a double-blind, randomized pilot study

The subjective efficacy and safety of intermittent administration of a hypnotic for insomnia was assessed, since such a regime may provide a potential means of reducing the risk of habituation and dependence. A total of 160 adult patients (mean 45 years) with chronic insomnia were treated for 2 weeks with zolpidem, 10 mg, either continuously or intermittently (five nights zolpidem, two consecutive nights placebo per week) in this multicentre, out-patient, pilot study. At the end of the 2-week treatment, patients subjectively estimated their nightly total sleep time as 6.96 +/- 1.19 h (from 6.07 +/- 1.25 h at baseline) and 6.94 +/- 1.30 h (from 5.72 +/- 1.46 h) after the continuous and intermittent treatments, respectively. Patients' reports did not indicate any differences between the two groups in global evaluation of impairment, sleep quality, or the incidence of adverse events. These results suggest that the efficacy and safety of zolpidem, 10 mg, are comparable whether the drug is administered every night or intermittently. Further studies with a broader well-defined patient base, are needed to confirm these data.