Sleep in Schizophrenia

Expanding the search for emerging mental ill health to safeguard student potential and vocational success in high school: A narrative review

AIM

Young people experiencing mental ill health are more likely than their healthy aged peers to drop out of high school. This can result in social exclusion and vocational derailment. Identifying young people at risk and taking action before an illness is established or school dropout occurs is an important goal. This study aimed to examine evidence for the risk markers and at risk mental states of the clinical staging model (stage 0-1b) and whether these risk states and early symptoms impact school participation and academic attainment.

METHOD

This narrative review assembles research from both the psychiatry and education literature. It examines stage 0 to stage 1b of the clinical staging model and links the risk states and early symptoms to evidence about the academic success of young people in high school.

RESULTS

In accordance with the clinical staging model and evidence from education literature, childhood trauma and parental mental illness can impact school engagement and academic progress. Sleep disturbance can result in academic failure. Undifferentiated depression and anxiety can increase the risk for school dropout. Subthreshold psychosis and hypomanic states are associated with functional impairment and high rates of Not in Employment, Education, or Training (NEET) but are not recognized in the education literature.

CONCLUSION

Risk markers for emerging mental ill health can be identified in education research and demonstrate an impact on a student's success in high school. Clear referral protocols need to be embedded into school life to reduce risk of progression to later stages of illness and support school participation and success.

The Mediating Effect of Alexithymia on the Relationship Between Schizotypal Traits and Sleep Problems Among College Students

A body of research has investigated the relationship between alexithymia and sleep problems, as well as the relationship between schizophrenia and alexithymia. However, there have been few studies on the relationships between the three. The current study explored the relationship between schizotypal traits and sleep problems among college students, and the potential role of alexithymia as a mediator of this relationship. The participants were all first-year students at a medical university in Guangdong province, China. A total of 2,626 college students participated. They were asked to complete a questionnaire that incorporated the Schizotypal Personality Questionnaire (SPQ), the Toronto Alexithymia Scale (TAS-20), and the Insomnia Severity Index (ISI). The results revealed a relatively high percentage of students with mild insomnia (74.8%) and a smaller percentage with moderate to severe insomnia (7.9%). Correlation analysis revealed that both the TAS-20 and ISI scores had significant positive correlations with the SPQ score (p < 0.01). There was also a significant positive correlation between the TAS-20 and ISI scores (p < 0.01). The ISI score was significantly influenced by the SPQ score in a direct way, and increased considerably with increases in the TAS-20 score, indicating the importance of alexithymia as a mediator. The mediation model was tested via regression analysis and the bias-corrected bootstrap method, and these results further confirmed the role of alexithymia as a mediator.

Sleep therapeutics and neuropsychiatric illness

Alterations in sleep are extremely common in patients with neuropsychiatric illness. In addition, sleep disorders such as insomnia, obstructive sleep apnea, rapid eye movement sleep behavior disorder, and circadian rhythm disorders commonly occur at a rate greater than the general population in neuropsychiatric conditions. Historically, sleep problems have been viewed as symptoms of associated neuropsychiatric disorders. However, there is increasing evidence suggesting a complex inter-relationship with possible bidirectional causality. The inter-relatedness of these conditions represents an opportunity for understanding mechanisms and improving clinical treatment. To the extent that sleep problems affect neuropsychiatric conditions, it may be possible to address sleep problems and have a positive impact on the course of neuropsychiatric illnesses. Further, some treatments for sleep disorders have direct effects on neuropsychiatric illnesses that may be unrelated to their effects on sleep disorders. Similarly, neuropsychiatric conditions and their treatments can affect sleep and sleep disorders. This article reviews available evidence on the effects of therapies for sleep disorders on neuropsychiatric conditions and also secondarily considers the impacts of therapies for neuropsychiatric conditions on sleep. Primary goals of this review are to identify gaps in current research, to determine the extent to which the cross-therapeutic effects of these treatments help to elucidate therapeutic or pathological mechanisms, and to assist clinicians in optimizing therapeutic choice in patients with sleep disorders and neuropsychiatric conditions.

Sleep problems and attenuated psychotic symptoms in youth at clinical high-risk for psychosis

There has been growing interest on the effect of sleep problems on psychotic and prodromal symptoms. The current study investigated cross-sectional relations between sleep problems and attenuated psychotic symptoms in a large sample of 740 youth at Clinical High Risk (CHR) for psychosis in an attempt to replicate previous findings and assess whether findings from general population samples and psychotic samples extend to this CHR sample. Sleep problems were found to be significantly positively associated with attenuated psychotic symptom severity. Sleep problems were also found to be more closely associated with certain specific prodromal symptoms (e.g., suspiciousness and perceptual abnormalities) than other attenuated psychotic symptoms. Further, we found that depression mediated the cross-sectional association between sleep problems and paranoid symptoms only. This adds to a growing body of evidence suggesting the mediation role of depression is more pronounced for paranoid-type psychotic symptoms as compared to other psychotic symptoms (e.g., hallucinations).

Severe Sleep Deprivation Causes Hallucinations and a Gradual Progression Toward Psychosis With Increasing Time Awake

Background: Going without sleep for long periods of time can produce a range of experiences, including perceptual distortions and hallucinations. Many questions, however, remain unanswered regarding the types of symptoms which are most reliably elicited, the time of symptom onset, and whether symptoms worsen over time toward psychotic decompensation. Since sleep deprivation exceeding 48 h is considered unethical today, an examination of historical studies with extreme sleep-loss duration is needed to obtain information about what happens during prolonged sleep loss. Methods: A systematic-review approach was used to identify experimental and observational studies of sleep deprivation in healthy people which describe the effects of prolonged sleep loss on psychopathological symptoms, without any date restriction. Results: A total of 476 articles were identified. Of these, 21 were eligible for inclusion. Duration of sleep loss ranged between 24 h and 11 nights (total 760 participants; average 72-92 h without sleep). All studies except one reported perceptual changes, including visual distortions (i.e., metamorphopsias), illusions, somatosensory changes and, in some cases, frank hallucinations. The visual modality was the most consistently affected (in 90% of the studies), followed by the somatosensory (52%) and auditory (33%) modalities. Symptoms rapidly developed after one night without sleep, progressing in an almost fixed time-dependent way. Perceptual distortions, anxiety, irritability, depersonalization, and temporal disorientation started within 24-48 h of sleep loss, followed by complex hallucinations and disordered thinking after 48-90 h, and delusions after 72 h, after which time the clinical picture resembled that of acute psychosis or toxic delirium. By the third day without sleep, hallucinations in all three sensory modalities were reported. A period of normal sleep served to resolve psychotic symptoms in many-although not all-cases. Conclusions: Psychotic symptoms develop with increasing time awake, from simple visual/somatosensory misperceptions to hallucinations and delusions, ending in a condition resembling acute psychosis. These experiences are likely to resolve after a period of sleep, although more information is required to identify factors which can contribute to the prevention of persistent symptoms.

Sleep quality, psychological symptoms, and psychotic-like experiences

Poor sleep quality has been repeatedly linked to the entire psychosis continuum, including psychotic-like experiences (PLEs); however, sleep dysfunction is a component of several other psychopathologies that have also been linked to increased risk for PLEs, including depression, anxiety, and post-traumatic stress disorder (PTSD). It has yet to be examined if PLEs are a significant risk factor for poor sleep quality or if this sleep dysfunction is better accounted for by comorbid psychopathology. In 2687 undergraduates, PLEs were evaluated using the positive items of the Prodromal Questionnaire. Symptoms of anxiety, depression, and PTSD were also assessed, as was sleep quality. Mediation analysis using PROCESS was conducted to determine if poor sleep quality associated with PLEs was in fact more associated with symptoms of other psychopathologies. Symptoms of depression and PTSD mediated the relationship between PLEs and sleep quality, though anxiety symptoms did not. These findings suggest that treating symptoms of depression and PTSD may improve multiple domains of psychotic illness.

Childhood trauma, depression, and sleep quality and their association with psychotic symptoms and suicidality in schizophrenia

This study involved the examination of the relationship between childhood trauma and both psychotic symptoms and suicidality in patients with schizophrenia after controlling for the possible confounding factors, such as clinical features, depression, and sleep quality. The Childhood Trauma Questionnaire-Short Form, Positive and Negative Syndrome Scale (PANSS), Calgary Depression Scale for Schizophrenia (CDSS), Pittsburgh Sleep Quality Index (PSQI), and the suicidality subscale of Mini-International Neuropsychiatric Interview (MINI) were administered to 199 patients with schizophrenia. We used sequential multiple stepwise regression analyses in which positive symptoms, negative symptoms, overall psychopathology, total symptoms of schizophrenia, and suicidality were dependent variables. Depressive symptomatology and childhood physical abuse significantly contributed to positive, negative, general psychopathology, and global schizophrenia symptomatology. Interestingly, general psychopathology scores were negatively associated with childhood physical neglect. Also, subjective sleep quality significantly contributed to positive schizophrenia symptoms. Although prior suicide attempts and depression were significant antecedents of suicidal ideation, no association between suicidality and both childhood trauma and sleep was found. Childhood physical abuse could have an impact on psychopathology in schizophrenia. In addition to childhood trauma, depression, sleep disturbances, and clinical features should be considered and inquired about in the course of clinical care of schizophrenia patients.

Sleep in Schizophrenia: Pathology and Treatment

Both subjective and objective assessments of sleep patterns in schizophrenia include a wide range of dyssomnias, with insomnia being the most frequently cited. Early and middle insomnia can range from mild disruption to total sleeplessness. Severe insomnia is a prodromal sign of clinical exacerbation or relapse. In general, most antipsychotic agents (APs) ameliorate this insomnia. However, in some schizophrenics APs can be associated with residual insomnia or with significant daytime somnolence. Furthermore, in some schizophrenics APs can induce or exacerbate comorbid sleep disorders such as restless legs syndrome, sleep-disordered breathing, and parasomnias such as sleepwalking.

The role of sleep dysfunction in the occurrence of delusions and hallucinations: A systematic review

BACKGROUND

Sleep dysfunction is extremely common in patients with schizophrenia. Recent research indicates that sleep dysfunction may contribute to psychotic experiences such as delusions and hallucinations.

OBJECTIVES

The review aims to evaluate the evidence for a relationship between sleep dysfunction and individual psychotic experiences, make links between the theoretical understanding of each, and highlight areas for future research.

METHOD

A systematic search was conducted to identify studies investigating sleep and psychotic experiences across clinical and non-clinical populations.

RESULTS

66 papers were identified. This literature robustly supports the co-occurrence of sleep dysfunction and psychotic experiences, particularly insomnia with paranoia. Sleep dysfunction predicting subsequent psychotic experiences receives support from epidemiological surveys, research on the transition to psychosis, and relapse studies. There is also evidence that reducing sleep elicits psychotic experiences in non-clinical individuals, and that improving sleep in individuals with psychosis may lessen psychotic experiences. Anxiety and depression consistently arise as (partial) mediators of the sleep and psychosis relationship.

CONCLUSION

Studies are needed that: determine the types of sleep dysfunction linked to individual psychotic experiences; establish a causal connection between sleep and psychotic experiences; and assess treatments for sleep dysfunction in patients with non-affective psychotic disorders such as schizophrenia.

Sleep Disorders Among People With Schizophrenia: Emerging Research

Up to 80 % of individuals with schizophrenia spectrum disorders experience sleep disturbances, which impact physical and mental health, as well as quality of life. In this paper, we review and integrate emerging literature, published between 2012 and 2014, regarding approaches to diagnosis and treatment of major sleep disorders for people with schizophrenia spectrum disorders, including insomnia, obstructive sleep apnea (OSA), circadian rhythm dysfunction, and restless legs syndrome (RLS). We advocate for (1) the need to evaluate the utility of nonpharmacological approaches in people with schizophrenia spectrum disorders; (2) documentation of guidelines to assist providers in clinically tailoring such interventions when their clients experience positive, negative, and/or cognitive symptoms; (3) research on the best ways providers can capitalize on clients' self-identified needs and motivation to engage in sleep treatments through shared decision making; and (4) the importance of investigating whether and how mental health and sleep treatment services should be better connected to facilitate access for people with schizophrenia spectrum disorders. Assessment and tailored treatment of sleep disorders within mental health treatment settings has the potential to reduce sleep problems and improve functioning, quality of life, and recovery of this population.

The role of noise in clinical environments with particular reference to mental health care: A narrative review

BACKGROUND

There is a large literature suggesting that noise can be detrimental to health and numerous policy documents have promoted noise abatement in clinical settings.

OBJECTIVES

This paper documents the role of noise in clinical environments and its deleterious effects with a particular focus on mental health care. Our intention however, is to go beyond the notion that noise is simply undesirable and examine the extent to which researchers have explored the meaning of sound in hospital settings and identify new opportunities for research and practice.

DATA SOURCES AND REVIEW METHODS

This is a narrative review which has grouped the literature and issues in the field into themes concerning the general issues of noise in health care; sleep noise and hospital environments; noise in intensive care units; implications for service users and staff; and suggestions for new ways of conceptualising and researching clinical soundscapes. Data sources comprised relevant UK policy documents and the results of a literature search of Pubmed, Scopus and Web of Knowledge using terms such as noise, health, hospital, soundscape and relevant additional terms derived from the papers retrieved. In addition the references of retrieved articles were scanned for additional relevant material and historical items significant in shaping the field.

RESULTS

Excess unwanted noise can clearly be detrimental to health and impede recovery, and this is clearly recognised by policymakers especially in the UK context. We use the literature surveyed to argue that it is important also to see the noise in clinical environments in terms of the meaning it conveys and rather than merely containing unwanted sound, clinical environments have a 'soundscape'. This comprises noises which convey meaning, for example about the activities of other people, the rhythms of the day and the nature of the auditory community of the hospital. Unwanted sound may have unwanted effects, especially on those who are most vulnerable, yet this does not necessarily mean that silence is the better option. Therefore it is our contention that it is important to begin thinking about the social functions of sound in the mental health environment.

CONCLUSIONS

Whilst it can be stressful, sound can also be soothing, reassuring and a rich source of information about the environment as well. It may be used to secure a degree of privacy for oneself, to exclude others or as a source of solidarity among friends and colleagues. The challenge then is to understand the work that sound does in its ecological context in health care settings.

Actigraphic-measured sleep disturbance predicts increased positive symptoms in adolescents at ultra high-risk for psychosis: A longitudinal study

BACKGROUND

Sleep disturbance is prevalent among patients with psychosis, yet little is known about sleep health during the ultra high-risk (UHR) period. This study used actigraphy to evaluate sleep in healthy control (HC) and UHR adolescents to examine the relationship between sleep disturbance and psychosis symptoms at baseline and 12-month follow-up, as well as comparisons between objective and subjective measurements of sleep functioning in UHR youth.

METHOD

Thirty-six UHR and 31 HC youth participated in a baseline evaluation including 5 nights of actigraphy, subjective measurement of sleep health (Pittsburgh Sleep Quality Index; PSQI), and clinical interviews. Clinical measures were repeated with UHR youth (N=23) at a 12-month follow-up.

RESULTS

The actigraphy data indicated that UHR youth displayed increased wake time after onset (WASO), increased movements during sleep, and decreased efficiency compared to HC, and several markers of sleep disturbance including decreased efficiency, increased WASO, number of awakenings, and increased movements were associated with symptomatology in the UHR group. Interestingly, there were associations between actigraph and self-report indices of sleep duration and efficiency (at the trend level) but not awakenings. Several objective measures of sleep disturbance and one self-reported measure (disrupted continuity) predicted the longitudinal course of symptoms over 12 months in the UHR group.

CONCLUSIONS

Taken together, the results suggest a potential role for sleep problems in the etiology of schizophrenia, and highlight sleep health as a possible target for prevention/intervention efforts. Additionally, actigraphy represents an inexpensive, sensitive measurement providing unique information not captured by self-report, and may be an informative adjunct to UHR assessments.

Sleep-wake patterns in schizophrenia patients compared to healthy controls

OBJECTIVES

The aim of this study was to examine the differences between a sample of patients with schizophrenia and a sample of healthy controls in terms of sleep patterns and self-reported sleep quality and quality of life (QoL).

METHODS

Thirty-four schizophrenia outpatients (SP), 12 women and 22 men and 34 healthy subjects (HS), 15 women and 19 men, participated in this study. Wrist-actigraphy recordings and a sleep diary were used for sleep-wake cycle assessment. The quality of sleep was measured using the Pittsburgh Sleep Quality Index (PSQI), the QoL was evaluated using the World Health Organization Quality of Life - Abbreviated version (WHOQOL-Bref). The Positive and Negative Syndrome Scale (PANSS) was used for psychopathology assessment.

RESULTS

Patients sleep more at night, but have poorer sleep efficiency, than HS. Sleep latency and nighttime awakenings were significantly higher in SP. Self-reported QoL scores were significantly higher, in all four domains, in HS. Scores on PSQI were significantly higher in SP, indicating a worse quality of sleep. Two disturbed patterns of sleep-wake phase were found in SP: advance sleep-phase syndrome (ASPS) (N = 3) and irregular sleep-wake rhythm (N = 3).

CONCLUSION

Schizophrenia patients have more disturbed sleep-wake patterns and poor sleep quality and quality of life compared with healthy controls.

A microstructural study of sleep instability in drug-naive patients with schizophrenia and healthy controls: sleep spindles, rapid eye movements, and muscle atonia

This study aimed at characterizing the functional stability of sleep in schizophrenia by quantifying dissociated stages of sleep (DSS), and to explore their correlation with psychopathology. The sleep of 10 first-break, drug-naive young adults with schizophrenia and 10 controls was recorded. Four basic DSS patterns were scored: 1) the transitional EEG-mixed intermediate stage (EMIS); 2) Rapid-eye-movement (REM) sleep without rapid eye movement (RSWR); 3) REM sleep without atonia (RSWA); and 4) non-REM sleep with rapid eye movements. An intermediate sleep (IS) score was calculated by summing EMIS and RSWR scores, and the durations of intra-REM sleep periods IS (IRSPIS) and IS scored "at the expense" of REM sleep (ISERS) were determined. Patients were administered the Brief Psychiatric Rating Scale (BPRS) at the time of recording. Proportions of each DSS variables over total sleep time and proportions of IRSPIS and ISERS over REM sleep duration were compared between patients and controls. Correlation coefficients between DSS variables and BPRS total scores were calculated. The proportion of total DSS did not differ between patients and controls. Among DSS subtypes, RSWA was significantly increased in patients while other comparisons showed no significant differences. Significant positive correlations were found between BPRS scores and proportions of DSS, IS, RSWR, IRSPIS and ISERS over total sleep and REM sleep durations. These results demonstrate the functional instability of REM sleep in first-break, drug naive young adults with schizophrenia and unveil a pattern reminiscent of REM sleep behavior disorder. The significant correlation suggests that schizophrenia and REM sleep share common neuronal control mechanisms.

Treatment adherence and quality of sleep in schizophrenia outpatients

OBJECTIVE

Patients with schizophrenia (SZ) often present sleep complaints, and patients with sleep disturbances are at a greater risk for symptom worsening after antipsychotic discontinuation. Long-term adherence to antipsychotic treatment remains a challenge for clinicians, and the relationship between quality of sleep and treatment adherence in SZ outpatients has been poorly studied.

METHODS

In this cross-sectional, non-interventional study, 811 adult outpatients with a diagnosis of SZ were divided into two groups according to the presence (or absence) of sleep disturbances, and assessed using measures of symptom severity, quality and patterns of sleep, adherence/compliance to treatment, and family support degree.

RESULTS

Patients with sleep disturbances were significantly more symptomatic (p < 0.0001), and scored significantly higher on the Pittsburgh Sleep Quality Index (PSQI) as compared with patients without sleep disturbances (p < 0.0001). More compliant patients showed less sleep disturbances (p < 0.0001); moreover, patients with worse compliance to pharmacological treatment showed significantly higher scores on the PSQI (p < 0.0001). Regarding family support degree, patients with sleep disorders presented a lower family support (p = 0.0236), and patients with worse treatment adherence had worse family support (p < 0.0001).

CONCLUSIONS

Our findings show that SZ outpatients reporting sleep disturbances show greater symptom severity, and worse adherence/compliance to treatment, as well as a lower family support.

Sleep dysfunction and thalamic abnormalities in adolescents at ultra high-risk for psychosis

BACKGROUND

Sleep dysfunction is a pervasive, distressing characteristic of psychosis, yet little is known regarding sleep quality prior to illness onset. At present, it is unclear whether sleep dysfunction precedes the emergence of psychotic symptoms, signifying a core feature of the disorder, or if it represents a consequence of prolonged contact with aspects of schizophrenia and its treatment (e.g., medication use or neurotoxicity) or co-morbid symptoms (e.g., depressive and manic symptomatology). The current study examined sleep dysfunction in adolescents at ultra high-risk (UHR) for psychosis, relationships between sleep disturbances and psychosis symptoms, volume of an integral sleep-structure (thalamus), and associations between thalamic abnormalities and sleep impairment in UHR youth.

METHOD

Thirty-three UHR youth and 33 healthy controls (HC) participated in a self-assessment of sleep functioning (Pittsburgh Sleep Quality Index; PSQI), self and parent-report clinical interviews, and structural magnetic resonance imaging (MRI).

RESULTS

UHR adolescents displayed increased latency to sleep onset and greater sleep disturbances/disrupted continuity compared to HC youth, over and above concurrent mood symptoms. Among UHR youth, increased sleep dysfunction was associated with greater negative symptom severity but not positive symptoms. Compared to HC adolescents, UHR participants displayed decreased bilateral thalamus volume, which was associated with increased sleep dysfunction.

CONCLUSIONS

Sleep dysfunction occurs during the pre-psychotic period, and may play a role in the etiology and pathophysiology of psychosis. In addition, the relationship of disrupted sleep to psychosis symptoms in UHR youth indicates that prevention and intervention strategies may be improved by targeting sleep stabilization in the pre-psychotic period.

Schizophrenia as a disturbance of cortical sensory maps

Schizophrenia is a disorder characterized by a variety of symptoms, which among others include hallucinations, delusions and passivity experiences. It has been found that individuals with schizophrenia misattribute their own thoughts and actions to an outside agency (source monitoring deficits), which could account for psychotic experiences such as that of hearing voices. In order to explain the source-monitoring deficits as well as psychosis, it has been proposed that mechanisms that enable anticipation and recognition of sensory consequences of one’s own actions are impaired in schizophrenia. Importantly, such mechanisms may require accurate cortical sensory representations such as in the primary somatosensory cortex (S1). The establishment and maintenance of cortical sensory representations has been found to utilize a sleep-related brain rhythm known as spindling. Namely, in the perinatal period in humans and animals, and possibly also thereafter, spontaneous activity in the sensory periphery drives spindle activity in the developing cortical sensory areas, which then contributes to the formation of sensory representations that match bodily features. For example, muscle twitch-spindle sequences during sleep facilitate the formation and maintenance of S1 in accordance with the layout of musculature. This process has been proposed to continue throughout the lifespan and may be particularly important during periods of bodily changes (adolescence, menopause). In schizophrenia, the amount of sleep spindle activity is markedly reduced, which would be expected to result in insufficient cortical sensory representations and have relevance for the relative inability of individuals with schizophrenia to accurately recognize self-initiated actions.

Sleep abnormalities in schizophrenia may suggest impaired trans-thalamic cortico-cortical communication: towards a dynamic model of the illness

Schizophrenia is associated with a wide range of symptoms. These include auditory hallucinations, delusions, and experiences that one is not in control of one's own thoughts and actions, but that they are inserted by an outside agency. It has been proposed that a disturbance in the sense of self may account for many of these symptoms. This disturbance in turn may be associated with source monitoring deficits. In other words, individuals with schizophrenia may misattribute the source of their own thoughts and actions to an outside agency, which then results in the experience of psychosis such as that of hearing voices. To explain the source monitoring deficits, it has been proposed that this illness involves impairment in corollary discharge mechanisms. Corollary discharge refers to preparation of sensory systems that will be affected by an action in advance of that action, which then allows this action to be recognized as one's own. Current research on corollary discharges suggests that they may involve the thalamus, which is notably affected in schizophrenia in terms of volume loss. Sleep abnormalities in this illness also suggest thalamic dysfunction as sleep spindles, which are markedly reduced in schizophrenia, require intact thalamocortical interactions. In this review, evidence is presented that suggests that propagation of corollary discharges and sleep spindles may be two mechanistically related processes as both involve trans-thalamic cortico-cortical interactions. These interactions may be impaired in schizophrenia and characterization of their mechanism may constitute a step towards developing a dynamic model of schizophrenia.

Reduced overnight consolidation of procedural learning in chronic medicated schizophrenia is related to specific sleep stages

We previously reported that patients with schizophrenia failed to demonstrate normal sleep-dependent improvement in motor procedural learning. Here, we tested whether this failure was associated with the duration of Stage 2 sleep in the last quartile of the night (S2q4) and with spindle activity during this epoch. Fourteen patients with schizophrenia and 15 demographically matched controls performed a motor sequence task (MST) before and after a night of polysomnographically monitored sleep. Patients showed no significant overnight task improvement and significantly less than controls, who did show significant improvement. While there were no group differences in overall sleep architecture, patients showed significant reductions in fast sigma frequency power (45%) and in spindle density (43%) during S2q4 sleep at the electrode proximal to the motor cortex controlling the hand that performed the MST. Although spindle activity did not correlate with overnight improvement in either group, S2q4 sleep duration in patients significantly correlated with the plateau level of overnight improvement seen at the end of the morning testing session, and slow wave sleep (SWS) duration correlated with the delay in reaching this plateau. SWS and S2q4 sleep each predicted the initial level of overnight improvement in schizophrenia, and their product explained 77% of the variance, suggesting that both sleep stages are necessary for consolidation. These findings replicate our prior observation of reduced sleep-dependent consolidation of motor procedural learning in schizophrenia and link this deficit to specific sleep stages. They provide further evidence that sleep is an important contributor to cognitive deficits in schizophrenia.