Katharina Wulff

Sleep and circadian rhythm disruption in psychiatric and neurodegenerative disease.

Sleep and circadian rhythm disruption are frequently observed in patients with psychiatric disorders and neurodegenerative disease. The abnormal sleep that is experienced by these patients is largely assumed to be the product of medication or some other influence that is not well defined. However, normal brain function and the generation of sleep are linked by common neurotransmitter systems and regulatory pathways. Disruption of sleep alters sleep–wake timing, destabilizes physiology and promotes a range of pathologies (from cognitive to metabolic defects) that are rarely considered to be associated with abnormal sleep. We propose that brain disorders and abnormal sleep have a common mechanistic origin and that many co-morbid pathologies that are found in brain disease arise from a destabilization of sleep mechanisms. The stabilization of sleep may be a means by which to reduce the symptoms of — and permit early intervention of — psychiatric and neurodegenerative disease.

Efficacy of the novel antidepressant agomelatine on the circadian rest-activity cycle and depressive and anxiety symptoms in patients with major depressive disorder: a randomized, double-blind comparison with sertraline.

OBJECTIVEnThis study evaluates the efficacy of agomelatine, the first antidepressant to be an agonist at MT(1)/MT(2) receptors and an antagonist at 5-HT(2C) receptors, versus sertraline with regard to the amplitude of the circadian rest-activity cycle and depressive and anxiety symptoms in patients with major depressive disorder (MDD).nnnMETHODnOutpatients with DSM-IV-TR-defined MDD received either agomelatine 25 to 50 mg (n = 154) or sertraline 50 to 100 mg (n = 159) during a 6-week, randomized, double-blind treatment period. The study was conducted from 2005 to 2006. The main outcome measure was the relative amplitude of the individual rest-activity cycles, expressed as change from baseline to week 6 and collected from continuous records using wrist actigraphy and sleep logs. Secondary outcome measures were sleep efficiency and sleep latency, both derived from actigraphy, and efficacy on depression symptoms (17-Item Hamilton Depression Rating Scale total score and Clinical Global Impressions scale scores) and anxiety symptoms (Hamilton Anxiety Rating Scale total score and subscores).nnnRESULTSnA significant difference in favor of agomelatine compared to sertraline on the relative amplitude of the circadian rest-activity cycle was observed at the end of the first week (P = .01). In parallel, a significant improvement of sleep latency (P <.001) and sleep efficiency (P <.001) from week 1 to week 6 was observed with agomelatine as compared to sertraline. Over the 6-week treatment period, depressive symptoms improved significantly more with agomelatine than with sertraline (P <.05), as did anxiety symptoms (P <.05).nnnCONCLUSIONSnThe favorable effect of agomelatine on the relative amplitude of the circadian rest-activity/sleep-wake cycle in depressed patients at week 1 reflects early improvement in sleep and daytime functioning. Higher efficacy results were observed with agomelatine as compared to sertraline on both depressive and anxiety symptoms over the 6-week treatment period, together with a good tolerability profile. These findings indicate that agomelatine offers promising benefits for MDD patients.nnnTRIAL REGISTRATIONnwww.isrctn.org: ISRCTN49376288.

Sleep and circadian rhythm disruption in schizophrenia

Background Sleep disturbances comparable with insomnia occur in up to 80% of people with schizophrenia, but very little is known about the contribution of circadian coordination to these prevalent disruptions. Aims A systematic exploration of circadian time patterns in individuals with schizophrenia with recurrent sleep disruption. Method We examined the relationship between sleep-wake activity, recorded actigraphically over 6 weeks, along with ambient light exposure and simultaneous circadian clock timing, by collecting weekly 48 h profiles of a urinary metabolite of melatonin in 20 out-patients with schizophrenia and 21 healthy control individuals matched for age, gender and being unemployed. Results Significant sleep/circadian disruption occurred in all the participants with schizophrenia. Half these individuals showed severe circadian misalignment ranging from phase-advance/delay to non-24 h periods in sleep-wake and melatonin cycles, and the other half showed patterns from excessive sleep to highly irregular and fragmented sleep epochs but with normally timed melatonin production. Conclusions Severe circadian sleep/wake disruptions exist despite stability in mood, mental state and newer antipsychotic treatment. They cannot be explained by the individuals level of everyday function.

Sleep and circadian rhythm disturbances: multiple genes and multiple phenotypes.

Sleep is regulated by two broad mechanisms: the circadian system, which generates 24-h rhythms of sleep propensity and a wake-dependent homeostatic sleep process whereby sleep pressure increases during wake and dissipates during sleep. These, in turn, regulate multiple brain structures and neurotransmitter systems. In view of the complexity of sleep it is not surprising that there is considerable variation between individuals in both sleep timing and propensity. Furthermore, marked abnormalities in sleep are commonly encountered in psychiatric and neurodegenerative disorders. Teasing apart the genetic versus environmental contributions to normal and abnormal sleep is complex. Here we attempt to summarise what recent progress has been made, and what will be needed in the future to gain a more complete understanding of this fundamental aspect of physiology.

Evaluating the links between schizophrenia and sleep and circadian rhythm disruption

Sleep and circadian rhythm disruption (SCRD) and schizophrenia are often co-morbid. Here, we propose that the co-morbidity of these disorders stems from the involvement of common brain mechanisms. We summarise recent clinical evidence that supports this hypothesis, including the observation that the treatment of SCRD leads to improvements in both the sleep quality and psychiatric symptoms of schizophrenia patients. Moreover, many SCRD-associated pathologies, such as impaired cognitive performance, are routinely observed in schizophrenia. We suggest that these associations can be explored at a mechanistic level by using animal models. Specifically, we predict that SCRD should be observed in schizophrenia-relevant mouse models. There is a rapidly accumulating body of evidence which supports this prediction, as summarised in this review. In light of these emerging data, we highlight other models which warrant investigation, and address the potential challenges associated with modelling schizophrenia and SCRD in rodents. Our view is that an understanding of the mechanistic overlap between SCRD and schizophrenia will ultimately lead to novel treatment approaches, which will not only ameliorate SCRD in schizophrenia patients, but also will improve their broader health problems and overall quality of life.

Sleep and circadian rhythm disruption in social jetlag and mental illness.

Sleep and wake represent two profoundly different states of physiology that arise within the brain from a complex interaction between multiple neural circuits and neurotransmitter systems. These neural networks are, in turn, adjusted by three key drivers that collectively determine the duration, quality, and efficiency of sleep. Two of these drivers are endogenous, namely, the circadian system and a homeostatic hourglass oscillator, while the third is exogenous-our societal structure (social time). In this chapter, we outline the neuroscience of sleep and highlight the links between sleep, mood, cognition, and mental health. We emphasize that the complexity of sleep/wake generation and regulation makes this behavioral cycle very vulnerable to disruption and then explore this concept by examining sleep and circadian rhythm disruption (SCRD) when the exogenous and endogenous drivers of sleep are in conflict. SCRD can be particularly severe when social timing forces an abnormal pattern of sleep and wake upon our endogenous sleep biology. SCRD is also very common in mental illness, and although well known, this association is poorly understood or treated. Recent studies suggest that the generation of sleep and mental health shares overlapping neural mechanisms such that defects in these endogenous pathways result in pathologies to both behaviors. The evidence for this association is examined in some detail. We conclude this review by suggesting that the emerging understanding of the neurobiology of sleep/wake behavior, and of the health consequences of sleep disruption, will provide new ways to decrease the conflict between biological and societal timing in both the healthy and individuals with mental illness.

Disrupted Circadian Rhythms in a Mouse Model of Schizophrenia

Summary Sleep and circadian rhythm disruption has been widely observed in neuropsychiatric disorders including schizophrenia [1] and often precedes related symptoms [2]. However, mechanistic basis for this association remains unknown. Therefore, we investigated the circadian phenotype of blind-drunk (Bdr), a mouse model of synaptosomal-associated protein (Snap)-25 exocytotic disruption that displays schizophrenic endophenotypes modulated by prenatal factors and reversible by antipsychotic treatment [3, 4]. Notably, SNAP-25 has been implicated in schizophrenia from genetic [5–8], pathological [9–13], and functional studies [14–16]. We show here that the rest and activity rhythms of Bdr mice are phase advanced and fragmented under a light/dark cycle, reminiscent of the disturbed sleep patterns observed in schizophrenia. Retinal inputs appear normal in mutants, and clock gene rhythms within the suprachiasmatic nucleus (SCN) are normally phased both in vitro and in vivo. However, the 24 hr rhythms of arginine vasopressin within the SCN and plasma corticosterone are both markedly phase advanced in Bdr mice. We suggest that the Bdr circadian phenotype arises from a disruption of synaptic connectivity within the SCN that alters critical output signals. Collectively, our data provide a link between disruption of circadian activity cycles and synaptic dysfunction in a model of neuropsychiatric disease.

Blue light–filtering intraocular lenses: Review of potential benefits and side effects

Blue light-filtering intraocular lenses (IOLs) have become part of the modern cataract surgeons armamentarium and are widely used. Their advocates suggest they may protect against light-induced retinal damage and also affect the development or progression of age-related macular degeneration. Much of the evidence for photoprotection is theoretical or based on observations in cell culture or animal experiments, with little clinical information to date. Although arguments remain theoretical, there is now emerging clinical data on the use of these IOLs in patients looking at the benefits and potential side effects. In this review, we consider the background to the development of these IOLs, the evidence for a reduction in short-wavelength light exposure protecting retinal cells and function, and the possible disadvantages of IOLs resulting from their reduced light transmission. We place this information in context with regard to patients having cataract surgery and the day-to-day conditions in which they live.

Delayed sleep phase in severe obsessive-compulsive disorder: a systematic case-report survey.

INTRODUCTIONnTo study the prevalence of delayed sleep phase (DSP) in a cohort of inpatients with severe obsessive-compulsive disorder (OCD) and to identify clinical and demographic correlates.nnnMETHODSnA systematic retrospective case-report study of consecutive OCD admissions to a specialist inpatient unit from January 1995 to December 2003. Nursing and medical records of sleep, demographic, clinical, and other relevant details were recorded.nnnRESULTSnOf 194 eligible consecutive case reports, 187 were located, and nursing and medical reports of sleep were identified in all 187 (100%). Thirty-three patients (17.6%) fulfilled operationally defined criteria for DSP after exclusion of possible confounding factors. All the patients with DSP were unemployed. Phase-shifted patients were significantly younger than non-shifted patients (P=.019) and reported an earlier age of onset of their OCD (P=.005). There was a non-significant trend toward more severe OCD in the phase-shifted group, but they were not more depressed than their non-shifted counterparts.nnnCONCLUSIONnA substantial number of patients with severe, enduring OCD also suffer with DSP, which seems to be specifically linked to OCD as opposed to comorbid depression. Clarification of the etiology within DSP and its interaction with core OCD symptoms on clinical function and disability may identify new treatment targets. To this end, further studies of sleep in OCD using actigraphy and biological measures are indicated.

Impact of Cataract Surgery on Sleep in Patients Receiving Either Ultraviolet-Blocking or Blue-Filtering Intraocular Lens Implants

PURPOSEnAlthough visual impairment is a well-recognized consequence of cataract development, little is known about the ability of the melanopsin-based photosensitive retinal ganglion cells (pRGCs) to regulate sleep-wake timing in the presence of cataract. In this study, we replaced a cataractous natural crystalline lens with two different types of artificial intraocular lenses, a UV-blocking lens or a blue-filtering lens. We investigated the level of sleep disturbance before cataract surgery and any change in sleep due to improved light transmission following surgery and compared this in both types of intraocular lens.nnnMETHODSnQuality of sleep in 961 patients undergoing cataract surgery was assessed by administering the validated self-reported Pittsburgh Sleep Quality Index (PSQI) questionnaire. The PSQI distinguishes good sleepers from poor sleepers by scoring seven different sleep components over the last month, which are combined to produce an overall score for sleep quality. Patients received either an ultraviolet-blocking (UVB) clear intraocular lens (IOL) or a blue-filtering (BF) IOL. Questionnaires were completed four times: 1 month preoperatively and again 1, 6 (UVB-IOL only), and 12 months postoperatively.nnnRESULTSnHalf of the patients reported poor sleep in the presence of cataract in both the UVB-IOL (mean PSQI = 6.35; SD = 3.82) and BF-IOL (mean PSQI = 6.39; SD = 4.04) groups. Cataract removal improved overall sleep quality significantly 1 month postoperatively in the UVB-IOL (mean PSQI = 5.89; SD = 3.71) and BF-IOL (mean PSQI = 6.08; SD = 3.88) groups. Sleep latency also improved for the UVB-IOL (preoperative mean = 1.16; SD = 1.003) and BF-IOL (preoperative mean = 1.17; SD = 1.03) groups at 1 month (UVB-IOL group mean = 1.01; SD = 0.923 and BF-IOL group mean = 1.00; SD = 0.95), which was sustained at 6 months for the UVB-IOL group (mean = 1.02; SD = 0.93) and 12 months for both the UVB-IOL and BF-IOL groups (6 months: UVB-IOL group mean = 0.96; SD = 0.92 and for the BF-IOL group mean = 0.99; SD = 0.96).nnnCONCLUSIONSnOverall sleep quality and sleep latency improves after removal of cataract irrespective of the type of IOL implanted. These data show that implantation of BF-IOL does not have a negative impact on the sleep-wake cycle.