Open research questions in Sleep and related disorders

What the literature leaves open

• There is a need to understand the associations among sleep quality, depression, and social rhythm in people living with HIV. Longitudinal and interventional studies are needed to determine the impact of targeting these symptoms.

  Symptom-level associations among sleep quality, depression, and social rhythm in people living with HIV: a network analysis · 2026 · DOI

• The paper identifies a gap in the understanding of social determinant factors associated with short sleep in the U.S. and Canada. The paper also identifies a gap in the comparison of short sleep prevalence between the U.S. and Canada.

  A cross-national study examining social determinant factors on short sleep between the U.S. and Canada · 2026 · DOI

• Investigate the reliability and validity of CST-derived sleep measures in other populations. Examine the effects of CSTs on sleep outcomes. Develop methods to improve the accuracy and reliability of CST-derived sleep measures.

  Are different consumer sleep technologies measuring the same essential aspects of sleep? · 2026 · DOI

• The barin functional indicators associated with WM deficits in MDD patients with insomnia remain unclear. The contribution of insomnia to cognitive dysfunction, particularly working memory deficits, remains poorly understood. There is a need to investigate the relationship between insomnia and cognitive dysfunction in MDD patients, particularly in working memory (WM).

  Investigating working memory and brain activation in major depressive disorder with and without insomnia: insights from functional near-infrared spectroscopy (fNIRS) · 2026 · DOI

• The low internal consistency of the sleep disturbance measure was of concern. The sample size was limited to 175 children. The study only examined associations between child reported peer victimization and child reported sleep disturbance in a late childhood age group.

  Bidirectional Associations Between Relational and Physical Peer Victimization and Sleep Disturbance Among Boys and Girls in Late Childhood · 2026 · DOI

• Examine the bidirectional effects of peer victimization and sleep disturbance in different age groups. Investigate the role of gender in the peer victimization-sleep disturbance association. Explore the mechanisms underlying the relationship between peer victimization and sleep disturbance.

  Bidirectional Associations Between Relational and Physical Peer Victimization and Sleep Disturbance Among Boys and Girls in Late Childhood · 2026 · DOI

• One challenge is the potential overlap between CDS symptoms and sleep difficulties, which may lead to conflation. Another challenge is the need to control for depressive symptoms, which are strongly associated with both CDS and poorer sleep functioning. A third challenge is the need to use a multi-informant design to examine CDS, ADHD, and depressive symptoms in relation to sleep disturbance and circadian preference.

  Multi-informant Examination of Cognitive Disengagement Syndrome in Relation to Sleep and Circadian Preference in Early Adolescents · 2026 · DOI

• further examination of the association between CDS and sleep disturbance, - investigation of the relationship between CDS and circadian preference, - study of CDS in different age groups or populations

  Multi-informant Examination of Cognitive Disengagement Syndrome in Relation to Sleep and Circadian Preference in Early Adolescents · 2026 · DOI

• There is a gap in interventions for preschool-aged children's sleep problems. Prior interventions have primarily targeted infants and adolescents, with limited focus on preschool-aged children.

  Parent Perspectives on the Lights Out Online Program and Implications for Improvement · 2026 · DOI

• Further research is needed to examine relationships between RPE and objective markers of exertion and sleep in different populations and sports - Future studies could investigate the use of different devices and methods for measuring exertion and sleep - Research could also explore the development of personalized models for predicting exertion and sleep

  Sleep-related metrics that predict training intensity: an exploratory study in women's college athletics · 2026 · DOI

• The study identifies a gap in the literature regarding the sleep quality, adherence to the Mediterranean diet, and chronotype of amateur soccer players. There is a need to examine the differences in sleep quality, adherence to the Mediterranean diet, and chronotype among amateur soccer players, physically active individuals, and individuals with high sitting time.

  Sleep Quality and Adherence to the Mediterranean Diet in Male Young Adults: An Exploratory Study Among Amateur Soccer Players, Physically Active Individuals, and Individuals with High Sitting Time · 2026 · DOI

• The underlying neural pathways linking sleep's effect on cortisol stress recovery remain unclear. Prior research has not fully elucidated the neurobiological pathway linking objective sleep efficiency to cortisol stress recovery.

  Objective sleep efficiency links to cortisol stress recovery via dorsolateral prefrontal-hippocampal regulation · 2026 · DOI

• The study identifies a gap in understanding the mechanisms by which sleep interventions affect psychological outcomes. The relationship between sleep disturbances and depression is not fully understood.

  Sleep diary-derived parameters and sleep measures mediate the efficacy of transdiagnostic sleep and circadian intervention for depression · 2026 · DOI

• The incomplete framework of the neural signature of neuropsychological symptoms that are intimately correlated with heroin craving. The lack of understanding of the relationship between peripheral cytokines, white matter alterations, and insomnia in patients undergoing methadone maintenance treatment.

  Crosstalk of peripheral cytokine-white matter alteration-insomnia during methadone maintenance treatment · 2026 · DOI

• Investigating the relationship between chronotype and psychiatric symptoms in larger, more diverse samples - Examining the effects of chronobiology-informed interventions on clinical outcomes in individuals with SMI - Studying the underlying biological mechanisms linking psychopathology, frailty, and chronotype

  Commonalities in frailty and psychopathology predict chronotype across severe mental disorders from a comorbidity perspective · 2026 · DOI

• The mechanisms underlying the increased risk of physical comorbidities and poor outcomes in individuals with severe mental illnesses are not well understood. There is a lack of longitudinal studies examining the relationship between frailty, psychopathology, and chronotype in individuals with severe mental illnesses.

  Commonalities in frailty and psychopathology predict chronotype across severe mental disorders from a comorbidity perspective · 2026 · DOI

• One challenge is the difficulty of discontinuing benzodiazepines due to physical dependence and withdrawal symptoms. Another challenge is the lack of clarity on how to taper patients in a tolerable manner. The paper also notes the challenge of inter-individual variability in receptor sensitivity, binding affinity, and pharmacodynamic response.

  Pharmacological principles for safe benzodiazepine and Z-drug dose reduction · 2026 · DOI

• Randomized trials comparing linear with hyperbolic tapering are needed, - Empirical studies directly testing linear versus hyperbolic tapering are needed, - Research on the physiological mechanisms of benzodiazepine tolerance and adaptation is needed, - Studies on the effects of hyperbolic tapering on different populations and benzodiazepine types are needed

  Pharmacological principles for safe benzodiazepine and Z-drug dose reduction · 2026 · DOI

• The extent to which particular lifestyle factors explain relationships between mental health and outcome are unclear. Prior studies have not examined the mediating effects of lifestyle factors on relationships between mental health and functional outcomes in early adolescence.

  Mediating effects of healthy lifestyle factors on associations between mental health and functional outcomes in early adolescence · 2026 · DOI

• The study faces challenges in measuring sleep patterns in high-risk youth, including the need for reliable and valid measures. The study must account for nonlinear age-related changes in sleep patterns, which can be complex to model. The study must also consider the potential for differences in sleep patterns between high-risk and control youth to emerge at different developmental stages.

  Developmental trajectories of sleep in offspring of parents with mood disorders · 2026 · DOI

• There is a lack of understanding of which aspects of sleep distinguish high-risk youth from low-risk peers. There is a need to examine the developmental trajectories of sleep in high-risk youth to identify when differences emerge. Prior studies have not fully addressed the relationship between sleep and mood disorders in high-risk youth.

  Developmental trajectories of sleep in offspring of parents with mood disorders · 2026 · DOI

• The mechanisms linking sleep and oral function remain unclear. There is a lack of direct epidemiological evidence linking sleep duration and masticatory difficulties.

  Sleep duration and oral functional impairment: potential involvement of monocyte-related inflammation · 2026 · DOI

• Future prospective and longitudinal studies incorporating objective sleep measurements, comprehensive oral assess- ments, and detailed inflammatory profiling are needed to clarify causality and further elucidate the biological mecha- nisms linking sleep behavior, systemic inflammation, and oral functional impairment. In particular, studies integrat- ing objective assessments of masticatory performance with comprehensive oral health examinations may help to distinguish the contributions of specific oral conditions to 1 3Odontology perceived masticatory difficulties. Establishing these rela- tionships may further support the role of medical–dental collaboration in preventive healthcare by facilitating earlier identification and management of health problems among individuals at increased risk of systemic disease.

  Sleep duration and oral functional impairment: potential involvement of monocyte-related inflammation · 2026 · DOI

• The study faces challenges in terms of missing data, which are handled using multiple imputation. The study also faces challenges in terms of participant attrition, with 4,420 participants lost to follow-up. The study's findings may be limited by the self-reported nature of the sleep quality and asthma data.

  The impact of sleep quality on asthma incidence in middle-aged and older adults: evidence from a prospective cohort study · 2025 · DOI

• Current treatments for insomnia have limitations, such as side effects and potential dependency. Non-invasive brain stimulation techniques are a promising area of research for treating insomnia. There is a need for studies investigating the efficacy of alpha-frequency tACS for chronic insomnia.

  Medial parietal alpha-frequency transcranial alternating current stimulation for chronic insomnia: a randomized sham-controlled trial · 2025 · DOI

Most-cited papers in Sleep and related disorders

• The Pittsburgh sleep quality index: A new instrument for psychiatric practice and research · Psychiatry Research · 1989 · 29,714 citations
• Validation of the Insomnia Severity Index as an outcome measure for insomnia research · Sleep Medicine · 2001 · 7,097 citations
• Epidemiologic Study of Sleep Disturbances and Psychiatric Disorders · JAMA · 1989 · 3,360 citations
• Impact of sleep debt on metabolic and endocrine function · The Lancet · 1999 · 2,899 citations
• Insomnia as a predictor of depression: A meta-analytic evaluation of longitudinal epidemiological studies · Journal of Affective Disorders · 2011 · 2,413 citations
• Quantification of Sleepiness: A New Approach · Psychophysiology · 1973 · 2,012 citations
• Seasonal Affective Disorder · Archives of General Psychiatry · 1984 · 1,962 citations
• Athens Insomnia Scale: validation of an instrument based on ICD-10 criteria · Journal of Psychosomatic Research · 2000 · 1,503 citations
• A cognitive model of insomnia · Behaviour Research and Therapy · 2002 · 1,492 citations
• Test–retest reliability and validity of the Pittsburgh Sleep Quality Index in primary insomnia · Journal of Psychosomatic Research · 2002 · 1,411 citations

Most recent work

• Insufficient Sleep Among US Adolescents Across Behavioral Risk Groups · JAMA · 2026
• Perceptions of school start times and adolescent sleep by WHO region · Sleep Medicine · 2026
• A Matter of Minutes? The Magnitude of Pediatric Sleep Extension Interventions · PEDIATRICS · 2026
• Associations of total daily working hours encompassing unpaid care and domestic work with nonrestorative sleep and mental health in middle-aged Japanese men and women: A cross-sectional study · Social Science & Medicine · 2026
• Changing characteristics in the 2020s of fatal ‘novel’ benzodiazepine toxicity cases in Australia · Drug and Alcohol Dependence · 2026
• Sleep characteristics and risk factors in patients of insomnia comorbid with anxiety · BMC Psychology · 2026
• Before Attributing Poor Sleep Quality to e-Cigarette Consumption, All Factors Influencing Sleep Performance must be Included in the Analysis · International Journal of Advanced Multidisciplinary Research and Studies · 2026
• Data base of Characterization of self-reported sleep quality in male and female trained amateur triathletes: a descriptive study · Pensar en Movimiento: Revista de Ciencias del Ejercicio y la Salud · 2026
• Non-pharmacological interventions for sleep disorders in patients with Alzheimer's disease: An integrative review · Sleep Medicine · 2026
• Predictors of cognitive-behavioral therapy for insomnia (CBT-I) outcomes in individuals with psychiatric disorders: A retrospective observational cohort study · Psychiatry Research · 2026

Related topics in Psychology