Sleep disturbances in young subjects with visual dysfunction

Parental and Child Sleep: Children with Vision Impairment, Autistic Children, and Children with Comorbid Vision Impairment and Autism

BACKGROUND

Parents report associations between children's sleep disturbances and behaviors. Children with neurodevelopmental conditions (e.g., Williams Syndrome and autism) are consistently reported to experience increased sleeping problems. Sleep in children with vision impairment and children with a dual diagnosis of vision impairment and autism remains understudied.

METHODS

Our exploratory study compared sleep profiles in 52 children (aged 4-12 years) and their parents (n = 37), across four groups: children with vision impairment (VI; n = 9), autism (n = 10), comorbid vision impairment + autism (n = 6), and typically developing children (n = 27). Childhood sleep was measured using the parental report Childhood Sleep Habits Questionnaire and sleep diaries. Children's cognitive functioning was measured using digit span, semantic, and phonemic verbal fluency measures. Parental sleep was measured via the Pittsburgh Sleep Quality Index and Epworth Sleepiness Scale.

RESULTS

Clinically disordered sleep was reported in all child groups (p ≤ 0.001), particularly children with VI + autism. Age, not sleep quality/quantity, predicted cognitive task performance in TD and autistic groups, but not in VI and VI + autism groups. The child's diagnosis affected parental sleep, particularly in children with a dual diagnosis of VI + autism.

CONCLUSIONS

All participants experienced problematic sleep to varying degrees. Those most affected were children and parents in the VI + autism group, suggesting that autism may be the main driver of sleep problems in our sample.

Lighting the way: Exploring diurnal physical performance differences in school-aged visually impaired children and adolescents

Circadian rhythms play a pivotal role in governing various physiological processes, including physical performance. However, in individuals deprived of light perception, such as the blind, these circadian rhythms face disruption. This study aimed to explore the influence of disturbed circadian rhythms on short-term maximal physical performance in children and adolescents with visual impairment. Forty-five volunteers participated in this study, comprising 17 blind, 13 visually impaired, and 15 sighted participants. The participants underwent a series of tests assessing maximal isometric strength performance across two days. To mitigate the influence of morning session fatigue on the evening results, each participant group performed in two separate testing sessions (i.e. in the morning (7:00 h) and in the evening (17:00 h)) on non-consecutive days in a randomized and counterbalanced setting, with approximately 36 h of recovery time between sessions. To mitigate the impact of inter-individual differences on mean values and to account for the influence of age and sex on the studied variables, data were normalized. The outcomes revealed a significant diurnal variation in maximal isometric strength performance among sighted individuals, with peak performance observed in the evening. This pattern aligns with their well-entrained circadian rhythm. In contrast, blind and visually impaired individuals did not display significant diurnal variation, signaling disrupted circadian rhythms due to the absence of light perception. These findings emphasize the crucial consideration of circadian rhythms in assessments of physical performance, especially among participants with visual impairments.

Artificial light and neurodegeneration: does light pollution impact the development of Alzheimer's disease?

Two multidimensional problems of recent times - Alzheimer's disease and light pollution - seem to be more interrelated than previously expected. A series of studies in years explore the pathogenesis and the course of Alzheimer's disease, yet the mechanisms underlying this pathology remain not fully discovered and understood. Artificial lights which accompany civilization on a daily basis appear to have more detrimental effects on both environment and human health than previously anticipated. Circadian rhythm is affected by inappropriate lighting conditions in particular. The consequences are dysregulation of the sleep-wake cycle, gene expression, neuronal restructuring, brain's electricity, blood flow, metabolites' turnover, and gut microbiota as well. All these phenomena may contribute to neurodegeneration and consequently Alzheimer's disease. There is an increasing number of research underlining the complexity of the correlation between light pollution and Alzheimer's disease; however, additional studies to enhance the key tenets are required for a better understanding of this relationship.

Sleep Patterns in Children With Blindness: A Comparison With Normally Sighted Peers

Purpose

Studies showing problematic sleep patterns in blind and visually impaired children are often based on (parent) self-report. The purpose was to compare sleep patterns of blind children to normally sighted peers using objective measures.

Methods

In this cross-sectional study, 100 blind (best-corrected visual acuity <3/60) and 100 age- and gender-matched normally sighted children aged 7 to 17 years wore a digital activity monitoring device for 1 week. Sleep quantity (i.e., total sleep time and total time in bed) and sleep quality (number of awakenings, latency, efficiency, wake after sleep onset [WASO], and sleep fragmentation index) were measured. Adjusted linear regression analyses were used to model group differences in sleep parameters.

Results

Data of 163 children were included. Blind children spent significantly less total time in bed in minutes (β, -31; 95% confidence interval, -56 to -6) and had a lower total sleep time (-41; -66 to -17), smaller number of awakenings (-2.8; -4.5 to -1.0), a lower WASO (-10; -16 to -5), and a more efficient sleep pattern (1.5; 0.1 to 2.8) compared to normally sighted children.

Conclusions

Although sleep quantity and recommended hours of sleep per night were lower among blind children than normally sighted children, their sleep quality was better. This contradicts findings of self-report studies and warrants further studies to measure sleep objectively. Further, the discrepancy between previous findings and our findings regarding sleep quality may be explained by the house rules of the boarding schools attended by blind children, which may facilitate improved sleep hygiene.

An exploratory study of sleep habits in school-aged survivors of retinoblastoma

OBJECTIVE/BACKGROUND

Retinoblastoma is an ocular cancer diagnosed in early childhood. Previous research has indicated the impact of cancer treatment on sleep, but little is known about how sleep is impacted among survivors of retinoblastoma. The current study aimed to describe sleep habits of school-age survivors of retinoblastoma, to examine associations between sleep and quality of life, and to examine concordance between parent and child reports of sleep habits.

PATIENTS/METHODS

Sixty-nine survivors of retinoblastoma (Mage = 10.89, SD = 1.07, 50.7% female; 56.5% unilateral disease) and their caregivers participated, providing information on both self- and parent-reported sleep habits, quality of life, and demographic data.

RESULTS

Greater sleep concerns than national norms were reported by parents (bedtime resistance (t(58) = 2.69, p = .009), greater sleep onset delay (t(66) = 2.46, p = .017), shorter sleep duration (t(57) = 2.12, p = .038), increased daytime sleepiness (t(53) = 6.45, p= <.001)) and children (sleep location (t(61) = 2.39, p = .02), restless legs syndrome (t(62) = -2.21, p = .03), parasomnias (t(64) = 19.19, p=<.001)) . Both children and parents of children who received enucleation endorsed greater sleep concerns across several domains (e.g., electronic use before bed, sleep-disordered breathing). Child- and parent-reported sleep concerns were generally associated with decreased quality of life. Finally, child- and parent-report of sleep habits appeared generally consistent.

CONCLUSIONS

Survivors of retinoblastoma experience sleep difficulties. As such, assessment and targeted intervention is important to mitigate any effects on quality of life. Future research should examine sleep habits of survivors of retinoblastoma across cultures and developmental periods.

The Effect of Self-Reported Visual Impairment and Sleep on Cognitive Decline: Results of the Hispanic Community Health Study/Study of Latinos

BACKGROUND

Visual impairment could worsen sleep/wake disorders and cognitive decline.

OBJECTIVE

To examine interrelations among self-reported visual impairment, sleep, and cognitive decline in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) Miami-site.

METHOD

HCHS/SOL Miami-site participants ages 45-74 years (n = 665) at Visit-1, who returned for cognitive test 7-years later (SOL-INCA). Participants completed the National Eye Institute Visual Functioning Questionnaire (NEI-VFQ), validated sleep questionnaires and test for obstructive sleep apnea (OSA) at Visit-1. We obtained verbal episodic learning and memory, verbal fluency, processing speed, and executive functioning at Visit-1 and at SOL-INCA. Processing speed/executive functioning were added to SOL-INCA. We examined global cognition and change using a regression-based reliable change index, adjusting for the time lapse between Visit-1 and SOL-INCA. We used regression models to test whether 1) persons with OSA, self-reported sleep duration, insomnia, and sleepiness have an increased risk for visual impairment, 2a) visual impairment is associated with worse cognitive function and/or decline, and 2b) sleep disorders attenuate these associations.

RESULT

Sleepiness (β= 0.04; p < 0.01) and insomnia (β= 0.04; p < 0.001) were cross-sectionally associated with visual impairment, adjusting for sociodemographic characteristics, behavioral factors, acculturation, and health conditions. Visual impairment was associated with lower global cognitive function at Visit-1 (β= -0.16; p < 0.001) and on average 7-years later (β= -0.18; p < 0.001). Visual impairment was also associated with a change in verbal fluency (β= -0.17; p < 0.01). OSA, self-reported sleep duration, insomnia, and sleepiness did not attenuate any of the associations.

CONCLUSION

Self-reported visual impairment was independently associated with worse cognitive function and decline.

Sleep Challenges and Interventions in Children With Visual Impairment

PURPOSE

To examine sleep patterns in a large and heterogeneous group of children with visual impairment.

METHODS

A cross-sectional survey of parents of children with visual impairment was offered via the National Federation of the Blind and the National Organization for Albinism and Hypopigmentation.

RESULTS

Complete survey results were available for 72 participants, aged 1 to 16 years. Parents of 52 (72%) children reported that their child had cycles of good sleep and bad sleep, and 50 (69%) reported that their child's sleep patterns caused significant stress for them or their family. Scores on the Childhood Sleep Habits Questionnaire (CSHQ) increased (> 41) in 64 (89%) children, indicating a likely clinically significant sleep problem. When compared to normative data from children aged 4 to 10 years, children in the current sample scored higher (more sleep problems) on all eight subscales on the CSHQ. The presence of comorbid developmental delay was most strongly associated with sleep problems. Supplemental melatonin and improving daytime and nighttime schedules or routines were reported as the most helpful for sleep. Many families reported a need for further information regarding melatonin use as a supplement.

CONCLUSIONS

A high proportion of children with visual impairment experience clinically meaningful sleep problems, regardless of degree of light perception or visual acuity. There is a strong need for increased awareness and screening for sleep problems in this population. Potential treatment modalities, including supplemental melatonin, should be discussed with families. [J Pediatr Ophthalmol & Strabismus. 2022;59(2):77-86.].

Non-visual Opsins and Novel Photo-Detectors in the Vertebrate Inner Retina Mediate Light Responses Within the Blue Spectrum Region

In recent decades, a number of novel non-visual opsin photopigments belonging to the family of G protein- coupled receptors, likely involved in a number of non-image-forming processes, have been identified and characterized in cells of the inner retina of vertebrates. It is now known that the vertebrate retina is composed of visual photoreceptor cones and rods responsible for diurnal/color and nocturnal/black and white vision, and cells like the intrinsically photosensitive retinal ganglion cells (ipRGCs) and photosensitive horizontal cells in the inner retina, both detecting blue light and expressing the photopigment melanopsin (Opn4). Remarkably, these non-visual photopigments can continue to operate even in the absence of vision under retinal degeneration. Moreover, inner retinal neurons and Müller glial cells have been shown to express other photopigments such as the photoisomerase retinal G protein-coupled receptor (RGR), encephalopsin (Opn3), and neuropsin (Opn5), all able to detect blue/violet light and implicated in chromophore recycling, retinal clock synchronization, neuron-to-glia communication, and other activities. The discovery of these new photopigments in the inner retina of vertebrates is strong evidence of novel light-regulated activities. This review focuses on the features, localization, photocascade, and putative functions of these novel non-visual opsins in an attempt to shed light on their role in the inner retina of vertebrates and in the physiology of the whole organism.

Time-Varying Light Exposure in Chronobiology and Sleep Research Experiments

Light exposure profoundly affects human physiology and behavior through circadian and neuroendocrine photoreception primarily through the melanopsin-containing intrinsically photosensitive retinal ganglion cells. Recent research has explored the possibility of using temporally patterned stimuli to manipulate circadian and neuroendocrine responses to light. This mini-review, geared to chronobiologists, sleep researchers, and scientists in adjacent disciplines, has two objectives: (1) introduce basic concepts in time-varying stimuli and (2) provide a checklist-based set of recommendations for documenting time-varying light exposures based on current best practices and standards.

Sleep disruption considerations for Paralympic athletes competing at Tokyo 2020

The role of sleep is now recognized as an important component for success in athletic performance, and sleep is proposed to be one of the most effective recovery strategies available. Insufficient sleep is commonly reported among athletes while several factors have been put forward to explain why elite athletes might experience poor sleep. However, Paralympic athletes may be predisposed to a greater risk of poor sleep due to the associated complexities of some impairment types. In fact, clinical research has previously shown that individuals with disabilities have a higher prevalence of sleep disturbances when compared to their able-bodied counterparts. However, research and evidence-based practices regarding the sleep of elite Paralympic athletes are limited. Firstly, this narrative review aims to identify challenges associated with the Paralympic games to obtain optimal sleep. Secondly, identify the specific risk factors to sleep associated with particular impairment groups within the Paralympic population, and lastly to propose potential sleep-enhancing strategies that might be of relevance for Paralympic athletes. From this review, initial observations have identified that Paralympic athletes may have a heightened risk of sleep-related problems, and importantly highlighted the current lack of understanding within this population group. Furthermore, this review identified where further research is warranted to better understand how specific impairments impact sleep and, consequently, athletic performance. Additionally, this review highlighted that the forthcoming Tokyo games may offer a unique challenge for athletes trying to obtain optimal sleep, due to the anticipated thermal demands and the consequent irregular scheduling of events.

Lights Out: Examining Sleep in Children with Vision Impairment

Sleep is crucial for development across cognitive, physical, and social-emotional domains. Sleep quality and quantity impact domains of daytime functioning, attainment, and global development. Previous work has explored sleep profiles in typically developing children and children with developmental disorders such as Down syndrome and Williams Syndrome, yet there is a complete absence of published work regarding the sleep profiles of children with vision impairment aged 4–11 years. This is the first known study that examines the sleep profiles in children with vision impairment (n = 58) in comparison to 58 typically developing children (aged 4–11 years) in the UK. Sleep was measured using the Childhood Sleep Habits Questionnaire (CSHQ; parental report), actigraphy and sleep diaries. Results showed group differences in subjective CSHQ scores but not objective actigraphy measures. Surprisingly, the findings revealed disordered sleep (namely, poor sleep quantity) in both groups. Discordance between CSHQ and actigraphy measures could represent heightened awareness of sleeping problems in parents/caregivers of children with vision impairment. The implications of this study extend beyond group comparison, examining disordered sleep in ‘typically developing’ children, exploring the potential role of light perception and the importance of sleep quality and quantity in both groups.

Neonatal sleep development and early learning in infants with prenatal opioid exposure

The aim of this chapter is to examine the role of sleep and cognition in the context of the cumulative risk model examining samples of at-risk infants and maternal-infant dyads. The cumulative risk model posits that non-optimal developmental outcomes are the result of multiple factors in a child's life including, but not limited to, prenatal teratogenic exposures, premature birth, family socioeconomic status, parenting style and cognitions as well as the focus of this volume, sleep. We highlight poor neonatal sleep as both an outcome of perinatal risk as well as a risk factor to developing attentional and cognitive capabilities during early childhood. Outcomes associated with and contributing to poor sleep and cognition during infancy are examined in relation to other known risks in our clinical population. Implications of this research and recommendations for interventions for this population are provided.

Structural and functional consequences of PAX6 mutations in the brain: Implications for aniridia

The paired-box 6 (PAX6) gene encodes a highly conserved transcription factor essential for the proper development of the eye and brain. Heterozygous loss-of-function mutations in PAX6 are causal for a condition known as aniridia in humans and the Small eye phenotype in mice. Aniridia is characterized by iris hypoplasia and other ocular abnormalities, but recent evidence of neuroanatomical, sensory, and cognitive impairments in this population has emerged, indicating brain-related phenotypes as a prevalent feature of the disorder. Determining the neurophysiological origins of brain-related phenotypes in this disorder presents a substantial challenge, as the majority of extra-ocular traits in aniridia demonstrate a high degree of heterogeneity. Here, we summarize and integrate findings from human and rodent model studies, which have focused on neuroanatomical and functional consequences of PAX6 mutations. We highlight novel findings from PAX6 central nervous system studies in adult mammals, and integrate these findings into what we know about PAX6's role in development of the central nervous system. This review presents the current literature in the field in order to inform clinical application, discusses what is needed in future studies, and highlights PAX6 as a lens through which to understand genetic disorders affecting the human nervous system.

Effects of primary glaucoma on sleep quality and daytime sleepiness of patients residing at an equatorial latitude

AIM

To investigate the impact of primary glaucoma on sleep quality and daytime sleepiness of patients.

METHODS

Prospective cross-sectional study with consecutive sampling in South-East Asian population was performed. Validated questionnaires: the Pittsburg Sleep Quality Index (PSQI) and Epworth Sleepiness Scale (ESS) were administered prospectively. Subjects with non-glaucomatous optic neuropathy or concomitant retinal pathology were excluded. Glaucoma severity was based on HVF 24-2 perimetry. Binocular single vision was represented based on the better eye. Frequency of and predictive factors for poor sleep quality and excessive daytime sleepiness were compared.

RESULTS

A total of 79 primary open angle glaucoma (POAG), 27 primary angle-closure glaucoma (PACG) patients, and 89 controls were recruited. PACG patients had higher median PSQI scores (P=0.004) and poorer sleep quality (P<0.001). Compared to controls, PACG patients were 3.34 times more likely to have poor sleep quality (P=0.008), which remained significant after adjustment for demographics (P=0.016) and predictive variables (P=0.013). PACG patients have poorer sleep quality when visual acuity (VA) was 6/15 or worse (P=0.009). Univariate and multivariate analysis of predictive variables for poor sleep quality and daytime sleepiness did not find statistical significance.

CONCLUSION

PACG patients have poorer sleep quality but not daytime sleepiness. This is important in South-East Asian population with heavy disease burden. Evaluations on sleep disturbances can be considered to provide more holistic care.

Subjective and Objective Measures of Daytime Activity and Sleep Disturbance in Retinitis Pigmentosa

SIGNIFICANCE

Objectively measured limitations in daytime activity levels appear to be inextricably linked with sleep disturbances in retinitis pigmentosa (RP) patients, as well as associated with unemployment status and central vision loss. Innovative interventional strategies should be developed to help improve these issues and overall quality of life for RP patients.

PURPOSE

Novel sensor devices are emerging as valuable tools to objectively assess behavior. We used validated measures of wrist accelerometry to determine relationships between sleep, vision, and physical activity in RP subjects.

METHODS

For one week, 33 RP adults wore a wrist Actiwatch to detect movement during the day (average total activity counts) and disturbed sleep at night. They completed Early Treatment Diabetic Retinopathy Study visual acuity testing, Pelli-Robson contrast sensitivity, Goldmann V4e visual fields, and sleep diaries and validated questionnaires to assess their sleep and general health.

RESULTS

Greater wake after sleep onset time measured with actigraphy (i.e., sleep disruption) (P = .01), loss of visual acuity (P = .009), and nonemployment/student status (P = .002) were all significant predictors of reduced daytime average total activity counts in a multiple linear regression model, after adjusting for contrast sensitivity as a cooperative suppressor variable (P = .01) (R = 0.54). Fragmentation measured with actigraphy (i.e., restlessness during sleep) (P = .07) and decreased sleep quality ratings reported upon awakening by the participants in a sleep diary (P = .06) were each marginally associated with reduced daytime average total activity counts, whereas nonemployment/student status, reduced visual acuity, and contrast sensitivity were still significant predictors. Objective and subjective measures of sleep or daytime activity were not statistically significantly correlated (P > .05).

CONCLUSIONS

We find nonemployment/student status and sleep disturbances appear to be related to reduced daytime activity levels in adults with central vision loss due to RP. These findings underscore the importance of developing and evaluating interventions to help RP patients maintain engagement in productive activities and improve their disturbed sleep.

Chronotyping glaucoma patients with the Munich ChronoType Questionnaire: A case-control study

Purpose

The circadian clock is entrained to light by the intrinsically photosensitive retinal ganglion cells. Loss of these cells in glaucoma, an eye disease with loss of retinal ganglion cells as its key feature, might thus result in a change in chronotype. We aimed to compare the chronotype between glaucoma patients and healthy subjects.

Methods

We sent the Munich ChronoType Questionnaire to 221 glaucoma patients (response rate 81%); controls (primary control group) were primarily their spouses. After exclusion of shift workers and participants who woke-up due to an alarm clock on days off, 159 glaucoma patients (88 early, 21 moderate, 23 severe) and 163 controls remained. We calculated chronotype as the mid-sleep on days off, corrected for workweek accumulated sleep debt (MSF_sc). We compared means and variances between groups using Welch’s tests and F-tests, respectively. A secondary control group was recruited from participants in a citizen-science project (n = 17073) who completed an online questionnaire. A resampling method was applied to enable an age- and gender- matched comparison with the glaucoma patients.

Results

Compared to the primary control group, glaucoma did not affect the mean MSF_sc (controls 3:47; early, moderate, and severe glaucoma 3:40, 3:45, and 3:33, respectively [P = 0.62]). Chronotype variability seemed to increase with increasing disease severity (severe glaucoma versus controls: P = 0.023). The mean MSF_sc of the secondary control group was 3:50 (95% confidence interval 3:48 to 3:52); significantly later than that of the glaucoma patients (3:40; P = 0.024). Mean MSF_sc did not differ significantly between the control groups (P = 0.42).

Conclusions

No clear changes were found in the chronotype as determined by sleep phase in patients with glaucoma, especially not in early and moderate glaucoma. In severe glaucoma, chronotype variability seems to increase, possibly alongside a small advancement.

Global rise of potential health hazards caused by blue light-induced circadian disruption in modern aging societies

Mammals receive light information through the eyes, which perform two major functions: image forming vision to see objects and non-image forming adaptation of physiology and behavior to light. Cone and rod photoreceptors form images and send the information via retinal ganglion cells to the brain for image reconstruction. In contrast, nonimage-forming photoresponses vary widely from adjustment of pupil diameter to adaptation of the circadian clock. nonimage-forming responses are mediated by retinal ganglion cells expressing the photopigment melanopsin. Melanopsin-expressing cells constitute 1–2% of retinal ganglion cells in the adult mammalian retina, are intrinsically photosensitive, and integrate photic information from rods and cones to control nonimage-forming adaptation. Action spectra of ipRGCs and of melanopsin photopigment peak around 480 nm blue light. Understanding melanopsin function lets us recognize considerable physiological effects of blue light, which is increasingly important in our modern society that uses light-emitting diode. Misalignment of circadian rhythmicity is observed in numerous conditions, including aging, and is thought to be involved in the development of age-related disorders, such as depression, diabetes, hypertension, obesity, and cancer. The appropriate regulation of circadian rhythmicity by proper lighting is therefore essential. This perspective introduces the potential risks of excessive blue light for human health through circadian rhythm disruption and sleep deprivation. Knowing the positive and negative aspects, this study claims the importance of being exposed to light at optimal times and intensities during the day, based on the concept of the circadian clock, ultimately to improve quality of life to have a healthy and longer life.

Assessment of sleep in subjects with visual impairment: Comparison using subjective and objective methods

The objective of the present study was to verify the agreement between objective and subjective measures of sleep in people with and without visual impairment. Thirty-seven subjects with visual impairment participated in the study (19 blind without light perception and 18 low-vision), as well as 34 subjects with normal vision, with paired age and gender characteristics. For the subjective sleep evaluation, we used the Sleep Quality Index-PSQI and for the objective evaluation we used the ActiGraph GT3X+. Among the three analyzed groups, the blind was the only ones who presented differences between subjective and objective sleep duration (p = 0.021). Furthermore, the concordance between subjective and objective sleep duration (ICC = 0.388; p = 0.108) was not observed in blind subjects, and a greater variability of differences in sleep duration between the two methods was observed by the Bland Altman scatter plot. We concluded that the sleep duration obtained by PSQI did not show agreement for the objective sleep duration in blind subjects without light perception.

The U-shaped association between self-reported sleep duration and visual impairment in Korean adults: a population-based study

OBJECTIVE

This study aimed to investigate the association between self-reported sleep duration and visual impairment (VI) in Korean adults.

METHODS

This population-based, cross-sectional study examined ophthalmologic data of 16,374 Koreans aged 19 years and older from the 2010-2012 Korea National Health and Nutrition Examination Survey (KNHNES V). VI data (best-corrected distance visual acuity worse than 0.5 logMAR in the better-seeing eye) were obtained from direct ophthalmologic examinations, and data on self-reported sleep duration (≤5, 6, 7, 8, or ≥9 h/night) were obtained using questionnaires. Multiple logistic regression analysis was conducted to examine the association between self-reported sleep duration and VI, and we also adjusted for possible covariates.

RESULTS

The weighted VI prevalences (95% CIs) were 1.23% (0.70-1.76), 0.40% (0.10-0.70), 0.18% (0.04-0.31), 0.42% (0.26-0.58), and 0.66% (0.25-1.07) for participants who slept ≤5, 6, 7, 8, and ≥9 h/night, respectively. Even after adjusting for demographic factors (age and sex), lifestyle factors (household income, occupation, smoking status, regular exercise, and suicidal thoughts), and medical factors (diabetes, hypertension, stroke, and history of ocular surgery), greater risk of VI was found in the ≤5 h/night (OR = 3.23, 95% CI: 1.43-7.31) and ≥9 h/night (OR = 2.56, 95% CI: 1.03-6.41) groups, compared to the 7 h/night group.

CONCLUSIONS

In Korean adults, self-reported sleep duration and VI exhibited a U-shaped association. Both very short (≤5 h/night) and very long (≥9 h/night) sleep durations were significantly associated with increased VI.

Association between visual impairment and sleep duration: analysis of the 2009 National Health Interview Survey (NHIS)

Background

Visual impairment (VI) is associated with increased mortality and health factors such as depression and cardiovascular disease. Epidemiologic studies consistently show associations between sleep duration with adverse health outcomes, but these have not systematically considered the influence of VI. The aim of this study was to ascertain the independent association between VI and sleep duration using the National Health Interview Survey (NHIS) data. We also examined whether race/ethnicity influenced these associations independently of sociodemographic and medical characteristics.

Methods

Our analysis was based on the 2009 NHIS, providing valid sleep and vision data for 29,815 participants. The NHIS is a cross-sectional household interview survey utilizing a multistage area probability design. Trained personnel from the US census bureau gathered data during face-to-face interview and obtained socio-demographic, self-reported habitual sleep duration and physician-diagnosed chronic conditions.

Results

The mean age of the sample was 48 years and 56% were female. Short sleep and long sleep durations were reported by 49% and 23% of the participants, respectively. Visual impairment was observed in 10%. Multivariate-adjusted logistic regression models showed significant associations between VI and short sleep (OR = 1.6, 95% CI = 1.5-1.9 and long sleep durations (OR = 1.6, 95% CI = 1.3-1.9). These associations persisted in multivariate models stratified by race-ethnic groups.

Conclusion

Visual impairment was associated with both short and long sleep durations. Analysis of epidemiologic sleep data should consider visual impairment as an important factor likely to influence the amount of sleep experienced habitually.

Use of actigraphy for assessment in pediatric sleep research

The use of actigraphs, or ambulatory devices that estimate sleep-wake patterns from activity levels, has become common in pediatric research. Actigraphy provides a more objective measure than parent-report, and has gained popularity due to its ability to measure sleep-wake patterns for extended periods of time in the child's natural environment. The purpose of this review is: 1) to provide comprehensive information on the historic and current uses of actigraphy in pediatric sleep research; 2) to review how actigraphy has been validated among pediatric populations; and 3) offer recommendations for methodological areas that should be included in all studies that utilize actigraphy, including the definition and scoring of variables commonly reported. The poor specificity to detect wake after sleep onset was consistently noted across devices and age groups, thus raising concerns about what is an "acceptable" level of specificity for actigraphy. Other notable findings from this review include the lack of standard scoring rules or variable definitions. Suggestions for the use and reporting of actigraphy in pediatric research are provided.

Study protocol: a cross-sectional survey of seasonal affective disorder in Danish populations with and without severe visual impairments

INTRODUCTION

People with seasonal affective disorder (SAD) experience recurrent seasonal fluctuations in energy, mood and appetite. Retinal light exposure is suggested to play an important role in the pathogenesis and treatment of SAD. The aim of the study is to determine the prevalence of SAD in persons with severe visual impairments or blindness and to compare the results to a control group without visual impairments. Moreover, the authors wish to investigate whether SAD is correlated to the degree of impairment or to the diagnosis.

METHODS AND ANALYSIS

2781 persons with visual impairments ranging from total blindness to Snellen visual acuity 6/60 receive information letter and questionnaire by post. Completed questionnaires can be returned by post, email or telephone. For each respondent, all eye-related diagnoses will be obtained from national registries. Normally sighted and demographically matched control respondents will be contacted in a similar manner the subsequent winter season. The Seasonal Pattern Assessment Questionnaire rates seasonal variation within the six items: sleep, appetite, social activity, mood, energy and body weight. The Seasonal Pattern Assessment Questionnaire yields a Global Seasonal Score and a prevalence of SAD. Outcomes from the two groups will be compared. Moreover, outcomes from subgroups of the visually impaired population will be compared.

ETHICS AND DISSEMINATION

The study is approved by the Danish Data Protection Agency. Results will be published in a relevant scientific journal and be communicated to respondents and relevant institutions through cooperation with the Danish Association of the Blind.

Chemistry and biology of vision

Visual perception in humans occurs through absorption of electromagnetic radiation from 400 to 780 nm by photoreceptors in the retina. A photon of visible light carries a sufficient amount of energy to cause, when absorbed, a cis,trans-geometric isomerization of the 11-cis-retinal chromophore, a vitamin A derivative bound to rhodopsin and cone opsins of retinal photoreceptors. The unique biochemistry of these complexes allows us to reliably and reproducibly collect continuous visual information about our environment. Moreover, other nonconventional retinal opsins such as the circadian rhythm regulator melanopsin also initiate light-activated signaling based on similar photochemistry.

Melatonin for non-respiratory sleep disorders in visually impaired children

BACKGROUND

Exogenous melatonin helps in regulating the circadian rhythm and is widely used for the management of sleep disorders in visually impaired children.

OBJECTIVES

The aim of the review was to assess melatonin therapy for treatment of non-respiratory sleep disorders in visually impaired children, with regard to improvement in sleep habit, sleep scheduling and sleep maintenance, when compared with placebo or no treatment.

SEARCH METHODS

We searched the following databases between February 2011 and July 2011: the Cochrane Central Register of Controlled Trials (CENTRAL) 2011(1) searched on 4th February 2011; MEDLINE (1950 to June Week 3, 2011) searched on 20th June 2011; EMBASE (1980 to June Week 4, 2011) searched on 7th July 2011; CINAHL (1937 to 21 September 2011); the metaRegister of Controlled Trials (this includes ClinicalTrial.gov) searched 20 July 2011, and reference lists of papers identified after initial screening.

SELECTION CRITERIA

We planned to include randomized controlled trials (RCTs) and quasi-RCTs, including cross-over studies. Treatment would be exogenous melatonin. Control groups could be placebo, other medication for sleep disorders or no treatment. Outcomes sought were improved sleep with regard to timing and duration, quality of life and adverse events.

DATA COLLECTION AND ANALYSIS

Three review authors independently assessed trials for inclusion in the review.

MAIN RESULTS

We did not find any studies fulfilling the inclusion criteria, therefore no outcome data are reported.We identified nine studies after initial screening and, after further evaluation, we excluded these. The excluded studies involved a total of 163 individuals aged two years to 18 years. We excluded studies for three main reasons: they were non-randomized or case series studies, they were studies of people over 18 years of age or even where the study was randomised, the study population was mixed and results pertaining to the visually impaired cohort could not be independently evaluated. No significant adverse effects of melatonin were reported in these excluded studies.

AUTHORS' CONCLUSIONS

There is currently no high quality data to support or refute the use of melatonin for sleep disorders in visually impaired children. Placebo-controlled trials examining important clinical outcomes such as sleep quality, sleep latency, duration of sleep and night-time awakenings are needed. As the numbers of children meeting study inclusion criteria are likely to be low at individual sites, multicentre collaboration between developmental paediatricians, sleep physicians and other health care professionals is essential to achieve sufficient sample size for controlled studies. Such collaboration would help facilitate local recruitment at multiple sites, with study oversight being provided by paediatricians with expertise in sleep disorders. Participation of collaborators with experience in evidence-based practice research is also desirable due to the lack of protocols on melatonin therapy in the target population.

The role of melatonin in glaucoma: implications concerning pathophysiological relevance and therapeutic potential

Glaucoma is a frequent ophthalmologic condition leading to chronic progressive optic neuropathy, which can result in visual impairment and blindness. In addition, glaucoma is associated with a dysregulation of circadian rhythms, as well as with a high incidence of sleep disorders, depression, and anxiety. However, because of their high comorbidity in older age, these conditions have not received much scientific attention and are often undertreated. In the current paper, we review the available literature on the role of melatonergic mechanisms in glaucoma, regulation of circadian rhythms, and depression. The literature is presented as a narrative review, providing an overview on the most important and clinically relevant publications. Recently, there has been evidence for a progressive loss of intrinsically photosensitive retinal ganglion cells (ipRGC) because of oxidative stress in glaucoma. As ipRGC are responsible for the photic transduction to the circadian system and subsequent melatonin secretion, and melatonin is involved in the pathophysiology of circadian desynchronization, sleep disorder, and depression, an impairment of photo-dependent melatonergic signaling may be a common pathway connecting glaucoma with these comorbidities. This fact, as well as the proven retinal neuroprotective role of melatonin, suggests that melatonergic drugs provide a potentially promising treatment strategy supplementing the management of intraocular pressure by pharmacological and surgical measures. Additionally, multidisciplinary treatment focusing on depression and normalization of circadian rhythms might be beneficial for glaucoma patients. Furthermore, glaucoma might be a useful model for studying the pathophysiological interactions between the melatonergic, circadian, and mood systems.

Physiology of circadian entrainment

Mammalian circadian rhythms are controlled by endogenous biological oscillators, including a master clock located in the hypothalamic suprachiasmatic nuclei (SCN). Since the period of this oscillation is of approximately 24 h, to keep synchrony with the environment, circadian rhythms need to be entrained daily by means of Zeitgeber ("time giver") signals, such as the light-dark cycle. Recent advances in the neurophysiology and molecular biology of circadian rhythmicity allow a better understanding of synchronization. In this review we cover several aspects of the mechanisms for photic entrainment of mammalian circadian rhythms, including retinal sensitivity to light by means of novel photopigments as well as circadian variations in the retina that contribute to the regulation of retinal physiology. Downstream from the retina, we examine retinohypothalamic communication through neurotransmitter (glutamate, aspartate, pituitary adenylate cyclase-activating polypeptide) interaction with SCN receptors and the resulting signal transduction pathways in suprachiasmatic neurons, as well as putative neuron-glia interactions. Finally, we describe and analyze clock gene expression and its importance in entrainment mechanisms, as well as circadian disorders or retinal diseases related to entrainment deficits, including experimental and clinical treatments.

Melanopsin-expressing retinal ganglion cells: implications for human diseases

In the last decade, there was the seminal discovery of melanopsin-expressing retinal ganglion cells (mRGCs) as a new class of photoreceptors that subserve the photoentrainment of circadian rhythms and other non-image forming functions of the eye. Since then, there has been a growing research interest on these cells, mainly focused on animal models. Only recently, a few studies have started to address the relevance of the mRGC system in humans and related diseases. We recently discovered that mRGCs resist neurodegeneration in two inherited mitochondrial disorders that cause blindness, i.e. Leber hereditary optic neuropathy and dominant optic atrophy. The mechanism leading to mRGCs sparing in these blinding disorders, characterized by extensive and selective loss of RGCs, is currently unknown and under investigation. Other studies reported on mRGCs in glaucoma, on genetic variation of the melanopsin gene (OPN4) in seasonal affective disorder and on the role of mRGCs in migraineous photophobia. Our own data and studies from others have shown a significant reduction of mRGCs with aging. We anticipate that these studies will lead to many other investigations addressing the role of mRGCs and circadian photoreception in the pathogenesis of circadian and sleep abnormalities in neurodegenerative disorders.

Melanopsin retinal ganglion cells are resistant to neurodegeneration in mitochondrial optic neuropathies

Mitochondrial optic neuropathies, that is, Leber hereditary optic neuropathy and dominant optic atrophy, selectively affect retinal ganglion cells, causing visual loss with relatively preserved pupillary light reflex. The mammalian eye contains a light detection system based on a subset of retinal ganglion cells containing the photopigment melanopsin. These cells give origin to the retinohypothalamic tract and support the non-image-forming visual functions of the eye, which include the photoentrainment of circadian rhythms, light-induced suppression of melatonin secretion and pupillary light reflex. We studied the integrity of the retinohypothalamic tract in five patients with Leber hereditary optic neuropathy, in four with dominant optic atrophy and in nine controls by testing the light-induced suppression of nocturnal melatonin secretion. This response was maintained in optic neuropathy subjects as in controls, indicating that the retinohypothalamic tract is sufficiently preserved to drive light information detected by melanopsin retinal ganglion cells. We then investigated the histology of post-mortem eyes from two patients with Leber hereditary optic neuropathy and one case with dominant optic atrophy, compared with three age-matched controls. On these retinas, melanopsin retinal ganglion cells were characterized by immunohistochemistry and their number and distribution evaluated by a new protocol. In control retinas, we show that melanopsin retinal ganglion cells are lost with age and are more represented in the parafoveal region. In patients, we demonstrate a relative sparing of these cells compared with the massive loss of total retinal ganglion cells, even in the most affected areas of the retina. Our results demonstrate that melanopsin retinal ganglion cells resist neurodegeneration due to mitochondrial dysfunction and maintain non-image-forming functions of the eye in these visually impaired patients. We also show that in normal human retinas, these cells are more concentrated around the fovea and are lost with ageing. The current results provide a plausible explanation for the preservation of pupillary light reaction despite profound visual loss in patients with mitochondrial optic neuropathy, revealing the robustness of melanopsin retinal ganglion cells to a metabolic insult and opening the question of mechanisms that might protect these cells.

Sleep disturbances in visually impaired toddlers

OBJECTIVE

This study set out to describe sleep patterns in visually impaired (VI) children during the first 40 months of life compared to typically developing children. We also evaluated the influence of age, sex and the presence of other disabilities on sleep patterns.

PATIENTS AND METHODS

A sleep questionnaire was administered to 154 parents of 10- to 39-month-old children: 36 with visual impairment without associated disability; 68 with visual impairment and associated disabilities (cortical visual impairment); and 50 healthy controls. The groups were balanced by age and gender. The questionnaire was developed at the C. Mondino Institute of Neurology in Pavia, Italy with the aim of investigating sleep patterns and medical history.

RESULTS

Within the VI sample, sleep behaviour was not related to the presence of associated disabilities. Visually impaired children had higher sleep disturbance scores than healthy controls using the Richman Criteria. VI children took longer to fall asleep, and their nocturnal awakenings were longer, more frequent per night, and affected more nights per week compared to the controls.

CONCLUSIONS

The results of this study show that the sleep of VI children is characterized by increased difficulty in falling asleep and in sleeping through the night, compared with that of their healthy peers. These findings confirm those of other important studies on sleep in VI children and underline the importance of evaluating and taking into account sleep-wake cycle in the care of the VI child.

Non-visual photoreception: sensing light without sight

Recent work in blind human subjects has confirmed the presence of a non-visual ocular photoreceptive mechanism similar to that described in blind mice. This system appears to subserve circadian photic entrainment, the pupillary light response, and a number of other aspects of neurophysiology and behavior.

Circadian rhythm dysfunction in glaucoma: A hypothesis

The absence of circadian zeitgebers in the social environment causes circadian misalignment, which is often associated with sleep disturbances. Circadian misalignment, defined as a mismatch between the sleep-wake cycle and the timing of the circadian system, can occur either because of inadequate exposure to the light-dark cycle, the most important synchronizer of the circadian system, or reduction in light transmission resulting from ophthalmic diseases (e.g., senile miosis, cataract, diabetic retinopathy, macular degeneration, retinitis pigmentosa, and glaucoma). We propose that glaucoma may be the primary ocular disease that directly compromises photic input to the circadian time-keeping system because of inherent ganglion cell death. Glaucomatous damage to the ganglion cell layer might be particularly harmful to melanopsin. According to histologic and circadian data, a subset of intrinsically photoresponsive retinal ganglion cells, expressing melanopsin and cryptochromes, entrain the endogenous circadian system via transduction of photic input to the thalamus, projecting either to the suprachiasmatic nucleus or the lateral geniculate nucleus. Glaucoma provides a unique opportunity to explore whether in fact light transmission to the circadian system is compromised as a result of ganglion cell loss.

Occupational hazards in orthodontics: A review of risks and associated pathology

The purpose of this article was to review the occupational hazards related to the practice of orthodontics. A systematic approach was used to include all risks involved in an orthodontic practice. The classification of hazards was based on major sources of risks by system or tissue and by orthodontic office area (dental chair, laboratory, sterilization area, x-ray developing area). Potentially hazardous factors relate to the general practice setting; to specific materials and tools that expose the operator to vision and hearing risks; to chemical substances with known allergenic, toxic, or irritating actions; to increased microbial counts and silica particles of the aerosols produced during debonding; to ergonomic considerations that might have an impact on the provider's muscoleskeletal system; and to psychological stress with proven undesirable sequelae. The identification and elimination of these risk factors should be incorporated into a standard practice management program as an integral part of orthodontic education. Professional organizations can also assist in informing practitioners of potential hazards and methods to deal with them.

Violet and blue light blocking intraocular lenses: photoprotection versus photoreception

AIM

To analyse how intraocular lens (IOL) chromophores affect retinal photoprotection and the sensitivity of scotopic vision, melanopsin photoreception, and melatonin suppression.

METHODS

Transmittance spectra of IOLs, high pass spectral filters, human crystalline lenses, and sunglasses are used with spectral data for acute ultraviolet (UV)-blue photic retinopathy ("blue light hazard" phototoxicity), aphakic scotopic luminous efficiency, melanopsin sensitivity, and melatonin suppression to compute the effect of spectral filters on retinal photoprotection, scotopic sensitivity, and circadian photoentrainment.

RESULTS

Retinal photoprotection increases and photoreception decreases as high pass filters progressively attenuate additional short wavelength light. Violet blocking IOLs reduce retinal exposure to UV (200-400 nm) radiation and violet (400-440 nm) light. Blue blocking IOLs attenuate blue (440-500 nm) and shorter wavelength optical radiation. Blue blocking IOLs theoretically provide better photoprotection but worse photoreception than conventional UV only blocking IOLs. Violet blocking IOLs offer similar UV-blue photoprotection but better scotopic and melanopsin photoreception than blue blocking IOLs. Sunglasses provide roughly 50% more UV-blue photoprotection than either violet or blue blocking IOLs.

CONCLUSIONS

Action spectra for most retinal photosensitisers increase or peak in the violet part of the spectrum. Melanopsin, melatonin suppression, and rhodopsin sensitivities are all maximal in the blue part of the spectrum. Scotopic sensitivity and circadian photoentrainment decline with ageing. UV blocking IOLs provide older adults with the best possible rhodopsin and melanopsin sensitivity. Blue and violet blocking IOLs provide less photoprotection than middle aged crystalline lenses, which do not prevent age related macular degeneration (AMD). Thus, pseudophakes should wear sunglasses in bright environments if the unproved phototoxicity-AMD hypothesis is valid.

Daily illumination exposure and melatonin: influence of ophthalmic dysfunction and sleep duration

BACKGROUND

Ocular pathology lessens light's efficacy to maintain optimal circadian entrainment. We examined whether ophthalmic dysfunction explains unique variance in melatonin excretion of older adults over and above the variance explained by daily illumination, medical, and sociodemographic factors. We also examined whether ophthalmic dysfunction influences relationships between ambient illumination and melatonin.

METHODS

Thirty older adults (mean age = 69 years; Blacks = 42% and Whites = 58%) of both genders participated in the study. Demographic and health data were collected at baseline. Participants underwent eye exams at SUNY Downstate Medical Center, wore an actigraph to monitor illumination and sleep, and collected urine specimens to estimate aMT6s concentrations.

RESULTS

Hierarchical regression analysis showed that illumination factors explained 29% of the variance in aMT6s mesor. The proportion of variance explained by ophthalmic factors, sleep duration, and race was 10%, 2%, and 2%, respectively. Illumination factors explained 19% of the variance in aMT6s acrophase. The proportion of variance explained by ophthalmic factors, sleep duration, and race was 11%; 17%; and 2%, respectively. Controlling for sleep duration and race reduced the correlations between illumination and melatonin, whereas controlling for ophthalmic factors did not.

CONCLUSION

Ophthalmic exams showed that elevated intraocular pressure and large cup-to-disk ratios were independently associated with earlier melatonin timing. Lower illumination exposure also had independent associations with earlier melatonin timing. Conceivably, ophthalmic and illumination factors might have an additive effect on the timing of melatonin excretion, which in turn might predispose individuals to experience early morning awakenings.

Associations of ambient illumination with mood: contribution of ophthalmic dysfunctions

Evidence suggests that ocular pathology could reduce light-stimulated neuronal signaling to the suprachiasmatic nuclei. This study investigated associations of ambient illumination with moods, while considering the contribution of ophthalmic dysfunctions. Seventy Black (59%) and White (41%) Americans participated in the study. Their average age was 68.27+/-5.97 years; 73% were women. Baseline data included: physical health, mood, and sociodemographics. Ophthalmic factors including visual acuity, visual field defects, intraocular pressure, vertical and horizontal cup-to-disk ratios, and nerve-fiber-layer thickness were assessed at SUNY Downstate's eye clinic. The following week, participants wore the Actiwatch-L at home to monitor ambient illumination and sleep. Cosine analyses were performed on the logarithm of measured illumination, yielding the mesor and acrophase of daily illumination exposure. Sleep was estimated with an automatic scoring algorithm. Of the sample, 25% reported visual impairment and 85% reported good to excellent health; 27% were visually impaired according to American criteria. Partial correlation analyses showed an inverse correlation of daily illumination levels to depressed mood [r(p)=-0.33, P<0.05], when age, sex, ethnicity, income, BMI, diabetes, hypertension, respiratory disease, and habitual sleep duration were controlled. With further control for ophthalmic factors, the magnitude and significance of the correlation diminished [r(p)=-0.26, NS]. Individuals receiving daily illumination later in the day reported more depressed moods [r(p)=0.36, P<0.01]; of note, this correlation was not significant after control for the covariates [r(p)=0.18, NS]. Regression analysis indicated that the ophthalmic factors explained 13% of the variance in depression. Our results show that both the level and timing of ambient illumination are associated with mood. Furthermore, they suggest that visual impairment has a mediating effect on the associations of ambient illumination with depression, supporting the notion that ocular pathology lessens the efficacy of daily illumination in promoting positive moods.

The eye and sleep

BACKGROUND

Sleep-associated disorders of the eye are increasingly recognized. Disordered sleep has also been found in some blind patients.

METHODS

Review of the current state of knowledge of sleep-related eye disorders and blindness-related sleep disorders.

RESULTS

Incomplete eyelid closure during sleep (lagophthalmos) may be physiological but in some patients can cause significant symptoms. Nocturnal lagophthalmos may be a limiting factor in the surgical repair of some eyelid and orbital disorders. Normal eyelid closure has also been linked to the development of a number of ocular surface disorders. Sleep disorders are common, and obstructive sleep apnoea (OSA) the commonest. OSA is associated with a number of serious systemic diseases and also several eye disorders including floppy eyelid syndrome, optic neuropathy, glaucoma, anterior ischaemic optic neuropathy and papilloedema secondary to raised intracranial pressure. Treatment of OSA may help floppy eyelid syndrome, halt progression of associated glaucoma, and reduce intracranial pressure in patients with associated papilloedema. The diagnosis of OSA can only be made with formal sleep studies, but asking a small number of appropriate questions will help screen those patients who should be referred for sleep studies. Some blind patients have disordered sleep patterns due to disruption of the retinal input into the hypothalamic-pineal melatonin secreting apparatus. This can be alleviated by oral administration of melatonin.

CONCLUSIONS

Ophthalmologists should be aware of sleep-associated eye disorders and refer appropriate patients for formal sleep studies. Sleep abnormalities in blind patients should be enquired about and patients offered assessment and treatment by a sleep physician.