Smartphone viewing distance and sleep: an experimental study utilizing motion capture technology

Cognitive risk and behaviour related to the effects of mobile phone use on sleep quality: an analysis of data from Chinese college students

This study assessed the relationships among cognitive risk, phone use behaviors, and sleep quality. We used a questionnaire, which included the Pittsburgh Sleep Quality Index (PSQI), mobile phone use behaviours, and questionnaires on mobile phone use cognitive risk to gather information from 1204 college students. T-test, chi-square test, and Wilcoxon signed rank test were applied to test differences in measurement data. Generalized linear regression analysis was used to analyze the factors influencing sleep quality. The percentage of people with poor sleep quality significantly increased during COVID-19, with a significant increase in sleep latency and diurnal dysfunction and a significant decrease in sleep persistence, sleep disturbance, and sleep efficiency. The PSQI scores significantly decreased during the COVID-19 pandemic (0.27 and 0.34 for overall and females in the 'Often take a break' subgroup), only females in the 'Often increase the distance between the screen and the eyes' subgroup had a significant decrease in the PSQI score (0.37). Bedtime use and bedtime light use in females significantly increased during the epidemic. Regression analysis revealed that rest or increased screen distance significantly improved sleep quality compared to rarely rest or rarely increased screen distance and had a more significant effect on sleep quality during the COVID-19 pandemic compared to before. The time spent using a phone with lights off before bedtime was significantly associated with poor sleep quality. Often resting, increasing the distance between the screen and the eyes, reducing phone use time, and reducing the time of lights off when using mobile phones are all protective factors for sleep quality. Females were more often affected by poor sleep quality.

Delayed sleep-wake phase disorder and its related sleep behaviors in the young generation

Delayed sleep-wake phase disorder (DSWPD) is a sleep disorder in which the habitual sleep-wake timing is delayed, resulting in difficulty in falling asleep and waking up at the desired time. Patients with DSWPD frequently experience fatigue, impaired concentration, sleep deprivation during weekdays, and problems of absenteeism, which may be further complicated by depressive symptoms. DSWPD is typically prevalent during adolescence and young adulthood. Although there are no studies comparing internationally, the prevalence of DSWPD is estimated to be approximately 3% with little racial differences between Caucasians and Asians. The presence of this disorder is associated with various physiological, genetic and psychological as well as behavioral factors. Furthermore, social factors are also involved in the mechanism of DSWPD. Recently, delayed sleep phase and prolonged sleep duration in the young generation have been reported during the period of COVID-19 pandemic-related behavioral restrictions. This phenomenon raises a concern about the risk of a mismatch between their sleep-wake phase and social life that may lead to the development of DSWPD after the removal of these restrictions. Although the typical feature of DSWPD is a delay in circadian rhythms, individuals with DSWPD without having misalignment of objectively measured circadian rhythm markers account for approximately 40% of the cases, wherein the psychological and behavioral characteristics of young people, such as truancy and academic or social troubles, are largely involved in the mechanism of this disorder. Recent studies have shown that DSWPD is frequently comorbid with psychiatric disorders, particularly mood and neurodevelopmental disorders, both of which have a bidirectional association with the pathophysiology of DSWPD. Additionally, patients with DSWPD have a strong tendency toward neuroticism and anxiety, which may result in the aggravation of insomnia symptoms. Therefore, future studies should address the effectiveness of cognitive-behavioral approaches in addition to chronobiological approaches in the treatment of DSWPD.

TFOS Lifestyle: Impact of the digital environment on the ocular surface

Eye strain when performing tasks reliant on a digital environment can cause discomfort, affecting productivity and quality of life. Digital eye strain (the preferred terminology) was defined as "the development or exacerbation of recurrent ocular symptoms and/or signs related specifically to digital device screen viewing". Digital eye strain prevalence of up to 97% has been reported, due to no previously agreed definition/diagnostic criteria and limitations of current questionnaires which fail to differentiate such symptoms from those arising from non-digital tasks. Objective signs such as blink rate or critical flicker frequency changes are not 'diagnostic' of digital eye strain nor validated as sensitive. The mechanisms attributed to ocular surface disease exacerbation are mainly reduced blink rate and completeness, partial/uncorrected refractive error and/or underlying binocular vision anomalies, together with the cognitive demand of the task and differences in position, size, brightness and glare compared to an equivalent non-digital task. In general, interventions are not well established; patients experiencing digital eye strain should be provided with a full refractive correction for the appropriate working distances. Improving blinking, optimizing the work environment and encouraging regular breaks may help. Based on current, best evidence, blue-light blocking interventions do not appear to be an effective management strategy. More and larger clinical trials are needed to assess artificial tear effectiveness for relieving digital eye strain, particularly comparing different constituents; a systematic review within the report identified use of secretagogues and warm compress/humidity goggles/ambient humidifiers as promising strategies, along with nutritional supplementation (such as omega-3 fatty acid supplementation and berry extracts).

The association between time spent on screens and reading with myopia, premyopia and ocular biometric and anthropometric measures in 6- to 7-year-old schoolchildren in Ireland

PURPOSE

More time spent on near tasks has consistently been associated with the promotion of myopia. The World Health Organization advises limiting daily screentime to less than 2 h for children aged five and over. This study explored the relationship between time spent on screens and reading/writing with refractive status, ocular biometric and anthropometric factors in 6- to 7-year-olds in Ireland.

METHODS

Participants were 723 schoolchildren (377 boys [51.8%]), mean age 7.08 (0.45) years. The examination included cycloplegic autorefraction (1% cyclopentolate hydrochloride), ocular biometry (Zeiss IOLMaster), height (cm) and weight (kg). Screentime and reading/writing time were reported by parents/legal guardians by questionnaire. Myopia (≤-0.50D) and premyopia (>-0.50D ≤ 0.75D) risk assessments were performed using logistic regression, and multivariate linear regression was used to analyse continuous variables.

RESULTS

Reported daily screentimes were 31% <1 h, 49.5% 1-2 h, 15.6% 2-4 h and 3.9% >4 h. Reading/writing times were 42.2% frequently, 48.0% infrequently and 9.8% seldom/never. Linear regression, controlling for age and ethnicity, revealed >2 h/day on screens was associated with a more myopic spherical equivalent [β = -1.15 (95% confidence intervals {CIs}: 1.62-0.69, p < 0.001)], increased refractive astigmatism (β = 0.29, CI: 0.06-0.51, p = 0.01), shorter corneal radius (β = 0.12, CI: 0.02-0.22, p = 0.02), higher axial length/corneal radius (β = 0.06, CI: 0.03-0.09, p < 0.001), heavier weight (β = 1.60, CI: 0.76-2.45, p < 0.001) and higher body mass index (BMI) (β = 1.10, CI: 0.28-1.12, p < 0.001). Logistic regression, controlling for age and ethnicity, revealed daily screentime >2 h was associated with myopia (OR = 10.9, CI: 4.4-27.2, p = 0.01) and premyopia (OR = 2.4, CI: 1.5-3.7, p < 0.001). Frequent reading/writing was associated with screentime ≤2 h/day (OR = 3.2, CI: 1.8-5.8, p < 0.001).

CONCLUSION

Increased screentime was associated with a more myopic refraction, higher axial length/corneal radius ratio, increased odds of myopia, premyopia, higher degrees of astigmatism, increased weight, BMI and decreased reading/writing time. Dedicated education programmes promoting decreased screentime in children are vital to prevent myopia and support eye and general health.

"Leave your smartphone out of bed": quantitative analysis of smartphone use effect on sleep quality

Smartphones have become an integral part of people's everyday lives. Smartphones are used across all household locations, including in the bed at night. Smartphone screens and other displays emit blue light, and exposure to blue light can affect one's sleep quality. Thus, smartphone use prior to bedtime could disrupt the quality of one's sleep, but research lacks quantitative studies on how smartphone use can influence sleep. This study combines smartphone application use data from 75 participants with sleep data collected by a wearable ring. On average, the participants used their smartphones in bed for 322.8 s (5 min and 22.8 s), with an IQR of 43.7-456. Participants spent an average of 42% of their time in bed using their smartphones (IQR of 5.87-55.5%). Our findings indicate that smartphone use in bed has significant adverse effects on sleep latency, awake time, average heart rate, and HR variability. We also find that smartphone use does not decrease sleep quality when used outside of bed. Our results indicate that intense smartphone use alone does not negatively affect well-being. Since all smartphone users do not use their phones in the same way, extending the investigation to different smartphone use types might yield more information than general smartphone use. In conclusion, this paper presents the first investigation of the association between smartphone application use logs and detailed sleep metrics. Our work also validates previous research results and highlights emerging future work.

The Japanese version of the children's sleep habits questionnaire (CSHQ-J): A validation study and influencing factors

SUBJECT

This study aimed to validate the Japanese version of the Child's Sleep Habits Questionnaire (CSHQ-J) and identify which factors affect the CHSQ-J total score.

METHODS

The participants were 3158 children (aged 4-12 years) and their parent/guardian, as community samples from large, medium-sized, and small cities. Each parent/guardian filled in the questionnaire set (CSHQ-J, Pittsburgh Sleep Quality Index, demographic data: family structure, sleep environment, participants' present illness, and economic information); we also collected 51 clinical samples from our facility to calculate the cutoff score. According to the age of the participants in the original CSHQ (4-10 years), validation was assessed statistically via exploratory and confirmatory factor analyses and internal consistency (verified by Cronbach's α). Multivariate analysis was conducted to identify factors affecting the CSHQ-J total score.

RESULTS

We received responses from 2687 participants (response rate: 85%) and analyzed 1688 participants who were the age of the original CSHQ participants. The alpha coefficients of each subscale of the CSHQ-J ranged from 0.43 to 0.68. The cutoff score was 48 (sensitivity: 0.69, specificity: 0.79). The confirmatory and exploratory factor analyses did not converge. Multivariate analysis showed that the factors that significantly influenced the CSHQ-J total score were co-sleeping, supplemental sleep, and child's age. Present illness, especially adenoids, also significantly influenced CSHQ total score.

CONCLUSIONS

The CSHQ-J has adequate internal consistency and is useful for screening for pediatric sleep disorders. Supplemental sleep, habit of co-sleeping, and child's age should be considered when using the CSHQ-J as a screening tool for sleep problems in children.

Effect of a telehealth-based exercise intervention on the physical activity of patients with breast cancer: A systematic review and meta-analysis

Telehealth-based exercise intervention as a non-pharmacological intervention has gradually emerged in breast cancer (BC), which shows feasibility and high levels of patient satisfaction. This systematic review aims to identify the effect of telehealth-based exercise interventions on the physical activity (PA) of patients with BC. We searched CENTRAL, CINAHL, PsycINFO, EMBASE, PubMed, Web of Science, ClinicalTrials.gov, CNKI, Wanfang, VIP, and SinoMed. Study selection and quality appraisal were performed independently by two reviewers. The review protocol was registered in PROSPERO (CRD42022326484). Nine studies, which included 1127 patients with BC, were identified. Compared with usual care, the telehealth-based exercise intervention had a significantly positive effect on PA (Standardized mean difference (SMD) = 0.26, 95% confidence interval (CI) 0.09 to 0.43, P = 0.003), aerobic capacity (SMD = 0.20, 95% CI 0.03 to 0.38, P = 0.02), upper body function (Mean difference (MD) = −4.56, 95% CI −7.66 to −1.47, P = 0.004), upper muscle strength (SMD = 0.26, 95% CI 0.09 to 0.42, P = 0.002), lower muscle strength (SMD = −0.95, 95% CI −1.27 to −0.62, P < 0.00001), abdominal muscle strength (MD = 23.85, 95% CI 13.84 to 33.86, P < 0.000,01), fatigue (SMD = 0.56, 95% CI 0.13 to 1.00, P = 0.01), and quality of life (SMD = 0.26, 95% CI 0.04 to 0.49, P = 0.02). Conversely, anthropometric and body composition and pain did not differ significantly between the two groups. Telehealth-based exercise intervention improved PA, physical performance, fatigue, and quality of life of patients with BC compared with routine care, which should be promoted clinically as a comprehensive treatment for BC.

Sleep-Wake Disorders in Alzheimer's Disease: A Review

Alzheimer's disease (AD) is a multifactorial disease, and it has become a serious health problem in the world. Senile plaques (SPs) and neurofibrillary tangles (NFTs) are two main pathological characters of AD. SP mainly consists of aggregated β-amyloid (Aβ), and NFT is formed by hyperphosphorylated tau protein. Sleep-wake disorders are prevalent in AD patients; however, the links and mechanisms of sleep-wake disorders on the AD pathogenesis remain to be investigated. Here, we referred to the sleep-wake disorders and reviewed some evidence to demonstrate the relationship between sleep-wake disorders and the pathogenesis of AD. On one hand, the sleep-wake disorders may lead to the increase of Aβ production and the decrease of Aβ clearance, the spreading of tau pathology, as well as oxidative stress and inflammation. On the other hand, the ApoE4 allele, a risk gene for AD, was reported to participate in sleep-wake disorders. Furthermore, some neurotransmitters, such as acetylcholine, glutamate, serotonin, melatonin, and orexins, and their receptors were suggested to be involved in AD development and sleep-wake disorders. We discussed and suggested some possible therapeutic strategies for AD treatment based on the view of sleep regulation. In general, this review explored different views to find novel targets of diagnosis and therapy for AD.

Posture Feedback System with Wearable Speaker

Maintaining good posture when using a laptop or a smartphone can prevent computer vision syndrome and text neck syndrome. However, it is difficult to remain aware of posture during an activity. Thus, wearable systems with posture feedback can help maintain good posture during daily activities. In this paper, we propose a posture feedback system that uses a commercial wearable speaker, which has been used for music and video conferencing when working from home. To judge a user's posture as good or poor, we focus on estimating the distance between the user's eyes and the screen when using a laptop and the neck tilt when using a smartphone. To estimate the distance, we use an active sensing method with ultrasound sent from a wearable speaker to a microphone on a laptop or a smartphone. The sound pressure of ultrasound changes depending on the distance between the wearable speaker and the microphone. In addition, an active sensing method can be used to estimate neck tilt because the sound pressure changes depending on the angle between the wearable speaker and the microphone. When the system judges the user's posture as poor, it will provide auditory feedback by applying digital audio effects to audible sounds (i.e., audio being listened to). Audio signal processing is implemented as a web application so users can use our system easily and immediately. We conducted three experiments to verify the feasibility of our proposed method. The sound pressure changed depending on the distance and angle between a wearable speaker and a microphone, and the system could judge posture as good or poor at almost 100 % under the experimental conditions.

Evaluation of changes in skin characteristics due to the poor quality of sleep caused by smartphone usage

BACKGROUND

Blue wavelengths are thought to have an effect on circadian rhythms. Using a smartphone, which emits a 453 nm blue light, can worsen the quality of sleep.

AIMS

To study the skin changes caused by poor sleep quality induced by smartphone usage.

METHODS

The participants were 22 Korean women aged 20-39 years, with no sleep problems and a Pittsburgh Sleep Quality Index (PSQI) score of <5. The participants used a smartphone for 2 h before normal sleep hours. The measurement points were as follows: after a good sleep (D0), after bad sleep day 1 (D1), after bad sleep day 3 (D3), and after bad sleep day 7 (D7). The sleep time, wake-up time, shallow sleep rate, and sleeping time duration were recorded using a smartwatch.

RESULTS

The quality of their sleep deteriorated. The average time of falling asleep extended to 2 a.m., which was about 34 min later. Additionally, their skin moisture content decreased, and sebum content increased. Skin desquamation was increased, and skin gloss, transparency, and elasticity decreased mainly on the skin surface.

CONCLUSIONS

Sleep quality decreases with smartphone usage among people who do not usually use their smartphones before going to sleep and do not have any sleep problems. The results showed significant changes in skin optics and surface properties when the quality of sleep was degraded for 7 days.

Impact of pre-sleep habits on adolescent sleep: an Italian population-based study

OBJECTIVE

Several evidences demonstrate that pre-sleep habits may negatively impact adolescent sleep, yet few data exist on Italian population. This study aimed to investigate the relationship between pre-sleep habits, use of technology/activity and sleep in Italian adolescents.

METHODS

Self-report questionnaires including Italian version of School Sleep Habits Survey and use of technology/activity (eg smartphone, PC) at bedtime were administered to 972 adolescents (13-19 years) from Lombardia. We stratified the sample in five groups according to the age: Group I (13-14 years), Group II (15 years), Group III (16 years), Group IV (17 years), Group V (18-19 years).

RESULTS

Our descriptive analysis reveals a different sleep profile across age-groups: Group III showed highest percentage of bad sleep (26.7%) and frequent nocturnal awakenings (24.1%), Group V had the highest percentage of insufficient sleep (40,4%) and difficulty falling asleep (42.7%) and Group IV presented an elevated difficulty in waking up in the morning (70.1%). A significant negative correlation was found in total group between use of smartphone, internet and studying/doing homework and total sleep time. The use of smartphone, internet videogames, listening to music and studying/doing homework was positively associated with delayed bedtime.

CONCLUSIONS

This study confirms the great impact of pre-sleep habits, and in particular the use of technology on adolescent sleep. Our results demonstrate that sleep is strongly altered among Italian adolescents using electronic devices in evening. The type of technology may be related to specific sleep profile, emphasizing the importance of stratification analyses to identify associated factors to sleep problems.

Preliminary Results: The Impact of Smartphone Use and Short-Wavelength Light during the Evening on Circadian Rhythm, Sleep and Alertness

Smartphone usage strongly increased in the last decade, especially before bedtime. There is growing evidence that short-wavelength light affects hormonal secretion, thermoregulation, sleep and alertness. Whether blue light filters can attenuate these negative effects is still not clear. Therefore, here, we present preliminary data of 14 male participants (21.93 ± 2.17 years), who spent three nights in the sleep laboratory, reading 90 min either on a smartphone (1) with or (2) without a blue light filter, or (3) on printed material before bedtime. Subjective sleepiness was decreased during reading on a smartphone, but no effects were present on evening objective alertness in a GO/NOGO task. Cortisol was elevated in the morning after reading on the smartphone without a filter, which resulted in a reduced cortisol awakening response. Evening melatonin and nightly vasodilation (i.e., distal-proximal skin temperature gradient) were increased after reading on printed material. Early slow wave sleep/activity and objective alertness in the morning were only reduced after reading without a filter. These results indicate that short-wavelength light affects not only circadian rhythm and evening sleepiness but causes further effects on sleep physiology and alertness in the morning. Using a blue light filter in the evening partially reduces these negative effects.

Determinants of sleep quality in college students: A literature review

PURPOSE

To review the various determinants of sleep quality among college students.

METHODS

The PubMed, Web of Science and Cochrane Library databases were searched with the search string "sleep quality" AND "college students" for articles published between January 2007 and October 2017. Articles were excluded if they (1) examined sleep quality as a risk factor for other outcomes or (2) involved inpatients or participants under medical care.

RESULTS

The 112 identified studies were classified into categories according to the investigated determinants and their effect on sleep quality. Physical activity and healthy social relations improved sleep quality, while caffeine intake, stress and irregular sleep-wake patterns decreased sleep quality. Less consistent results were reported regarding eating habits and sleep knowledge, while proper napping during the day might improve overall sleep quality.

CONCLUSIONS

College students are vulnerable to different risk factors for sleep quality. When designing interventions to improve sleep quality among college students, the main determinants need to be taken into consideration.

Head forward flexion, lateral bending and viewing distance in smartphone users: A comparison between sitting and standing postures

BACKGROUND

Smartphones (SPs) are widely used by people of all age groups and genders. Users spend many hours per day on the SPs for different purposes, which imposes significant stress on their musculoskeletal system.

OBJECTIVES

This study explored head forward flexion, lateral bending angle, and viewing distance while working with a SP in sitting/standing postures and one-handed/two-handed grips. The users' performance as well as pain development were also investigated.

METHODS

Participants answered a questionnaire on pain experience before and after SP usage. Neck kinematics of 20 SP users were monitored by a motion analysis system while doing three tasks (typing, video watching, and reading) in sitting and standing postures. Performance was evaluated by number of typed words, amount of errors in typing, and total read words.

RESULTS

The results indicated a significant increase in pain complaints in neck and upper limbs after test completion. Working with SPs in sitting and standing postures were, respectively, associated with greater head forward flexion for watching and viewing distance for two-handed typing tasks. Higher left lateral bending values were measured for one-handed watching and reading tasks in standing posture. The performance measures were superior for two-handed grips in all conditions.

CONCLUSIONS

Overall, using SPs in sitting posture creates greater head forward flexion and lower lateral bending angles in all tasks and grip types. The findings of this study can be used to provide recommendations for SP users.

Blue-Light Levels Emitted from Portable Electronic Devices Compared to Sunlight

Over recent years, a technological revolution has taken place in which conventional lighting has been replaced by light emitting diodes (LEDs). Some studies have shown the possibility that blue light from these artificial sources could have deleterious effects on the retina. Considering that people spend a non-negligible time in front of screens from computers and mobile phones, the eyes receive blue light of different intensities depending on the source. Nevertheless, any study about the visual and non-visual effects of blue light must consider precise measurements taken from actual artificial sources. For this reason, we have analyzed the spectral emission of 10 different electronic devices and weighted them according to the hazard caused by blue light to the eyes, comparing the results with solar radiation simulated with a radiative transfer model. The maximum spectral irradiance of the measured electronic devices at 10 cm from the detector was located between 440 nm and 460 nm. The irradiance for blue light hazard ranged from 0.008 to 0.230 Wm−2 depending on the particular characteristics of each electronic device. In contrast, the solar radiances in the same spectral range are larger both under clear and cloudy conditions.

Quality of Sleep Among Bedtime Smartphone Users

Background

Exposure to light from viewing devices at night disturbs the circadian rhythm, especially sleep. The study aimed to assess (a) extent to which smart phones are used by medical undergraduate students during bedtime and to find their quality of sleep (b) the association of quality of sleep and cell phone variables.

Methods

A cross sectional observational study was conducted among 450 medical undergraduate students. The participants completed Pittsburgh Sleep Quality Index (PSQI) questionnaire and a validated semi structured questionnaire consisting of demographic details and cell phone variables.

Results

By dividing the subjects into three groups according to their usage (Group I <1 hour, Group II 1 to 2 hours, Group III >2 hours), Group III respondents had significant prolonged sleep latency, reduced sleep duration, sleep inefficiency and daytime sleep disturbances (P < 0.05). Lack of awareness about night shift mode, lying posture use while using phone during bedtime correlated with poor quality sleep (P < 0.05).

Conclusions

Awareness about the negative impact of evening exposure to viewing devices on sleep and health should be emphasized.

[Effects of anxiety and smartphone dependency on sleep quality among pregnant women with preterm labor]

Purpose

The purpose of this study was to investigate the effects of anxiety and smartphone dependency on sleep quality in pregnant women with preterm labor.

Methods

The participants of this study were 111 pregnant women who were between 20 and 37 weeks of gestation and experienced preterm labor. The data were collected from October 1, 2018 to October 25, 2019. The collected data were analyzed using descriptive statistics (frequency, percentage, and standard deviation), as well as the t-test, Pearson correlation coefficients, and hierarchical multiple regression.

Results

Significant negative correlations were found between anxiety and sleep quality and between smartphone dependency and sleep quality. Participants' history of preterm birth, pregnancy method, bowel movements, anxiety, and smartphone dependency significantly affected sleep quality, with an explanatory power of 18%.

Conclusion

In order to improve the quality of sleep, which is an important health-related factor for pregnant women experiencing preterm labor, it will be necessary to identify a history of premature birth, pregnancies achieved using artificial reproductive technology, bowel problems, and smartphone dependency in advance and to provide nursing interventions accordingly.

Towards a Sustainable Indoor Lighting Design: Effects of Artificial Light on the Emotional State of Adolescents in the Classroom

In recent years, articles have been published on the non-visual effects of light, specifically the light emitted by the new luminaires with light emitting diodes (LEDs) and by the screens of televisions, computer equipment, and mobile phones. Professionals from the world of optometry have raised the possibility that the blue part of the visible light from sources that emit artificial light could have pernicious effects on the retina. The aim of this work is to analyze the articles published on this subject, and to use existing information to elucidate the spectral composition and irradiance of new LED luminaires for use in the home and in public spaces such as educational centers, as well as considering the consequences of the light emitted by laptops for teenagers. The results of this research show that the amount of blue light emitted by electronic equipment is lower than that emitted by modern luminaires and thousands of times less than solar irradiance. On the other hand, the latest research warns that these small amounts of light received at night can have pernicious non-visual effects on adolescents. The creation of new LED luminaires for interior lighting, including in educational centers, where the intensity of blue light can be increased without any specific legislation for its control, makes regulatory developments imperative due to the possible repercussions on adolescents with unknown and unpredictable consequences.

Difference in autonomic nervous effect of blue light depending on the angle of incidence on the eye

Objective

Blue light has been attributed to the adverse biological effects caused by the use of smartphones and tablet devices at night. However, it is not realistic to immediately avoid nighttime exposure to blue light in the lifestyle of modern society, so other effective methods should be investigated. Earlier studies reported that inferior retinal light exposure causes greater melatonin suppression than superior retinal exposure. We examined whether the autonomic responses to blue light depends on the angle of incidence to the eye.

Results

In eight healthy subjects, blue light from organic electroluminescent lighting device (15.4 lx at subjects’ eye) was exposed from 6 angles (0º, 30º, 45º, 135º, 150º, and 180º) for 5 min each with a 10-min interval of darkness. After adjusting the order effect of angles, however, no significant difference in heart rate or autonomic indices of heart rate variability with the angle of incidence was detected in this study.

Perception of Sleep Disturbances due to Bedtime Use of Blue Light-Emitting Devices and Its Impact on Habits and Sleep Quality among Young Medical Students

Introduction

The use of blue light-emitting devices (smartphones, tablets, and laptops) at bedtime has negative effects on sleep due to light stimulation and/or problematic excessive use. We aimed to evaluate, among young medical students, if the perception of sleep disturbances due to bedtime use of these devices is consistent with healthier habits and a better sleep quality.

Materials and methods

294 medical students in medicine and pharmacy from the Faculty of Medicine and Pharmacy of Rabat, Morocco, took part in this anonymous and voluntary cross-sectional study and answered an electronic questionnaire. Student and Mann–Whitney U tests were used to compare variables between 2 groups based on their perception of sleep disturbances. The level of significance was p ≤ 0.05.

Results

286 students (97.3%) used a blue light-emitting smart device at bedtime before sleep, and sleep quality was poor (Pittsburgh Sleep Quality Index, PSQI > 5) in 101 students (35.3%). The perception of sleep disturbances due to this night usage was reported by 188 of them (65.7%). In this group, 154 (81.9%) used their device with all the lights turned off in the room (p=0.02), 34 (18.1%) put devices under pillows (p=0.04), 114 (60.6%) interrupted sleep to check messages (p < 0.001), and the mean duration use of these technologies at bedtime was 2 h ± 23 min per night (p=0.02). Also, the mean sleep duration was 6.3 hours ± 1.25 (p=0.04), 119 (63.3%) presented fatigue on waking more than one time per week (p=0.04), and 76 (40.4%) presented poor sleep quality (75.2% of the students with PSQI > 5) (p=0.005).

Conclusions

Despite the perception of sleep disturbances due to bedtime use of blue light-emitting devices, unhealthy sleep habits tend to be frequent in young medical students and worrying because it is associated to significant poor sleep quality.

Binocular Coordination during Smartphone Reading in Esophoric Patients

Purpose: To evaluate binocular coordination using video-oculography (VOG) during smartphone reading in patients with esophoria (EP) compared with control subjects.Patients and methods: Ten young and adult patients with EP (25.3 ± 7.3 years) and seven orthophoric or small-angle exophoric control subjects (25.7 ± 4.8 years) were examined. Eye movements were recorded during smartphone reading at 20, 30, and 50 cm using VOG. Differences in the horizontal fixation disparity at each distance between and within the groups were analyzed.Results: Horizontal esodeviation at 20 cm in the EP group (1.23° ± 2.00°) was significantly greater than that at 30 cm (-0.39° ± 0.73°; P = .027) and was significantly greater than horizontal exodeviation at 20 cm in the control group (-0.21° ± 0.17°; P < .001).Conclusion: The current findings suggest that the horizontal fixation disparities in the patients with EP deviate to eso-direction during smartphone use.

Quantification of accommodative response and visual performance in non-presbyopes wearing low-add contact lenses

PURPOSE

Digital eye strain encompasses a range of ocular and visual symptoms across all age groups. Recently, symptoms associated with accommodative or binocular vision stress have become a major problem, especially in young individuals. The purpose of this prospective, single-blinded study was to objectively quantify the accommodative response and visual performance of low-add soft contact lenses (CLs) in young non-presbyopic individuals.

METHODS

A daily disposable low-add bifocal design lens (low-add CL) was tested. It employs a centre-distance optical zone and peripheral zone with the added power of +0.50 D to support near vision. Sixteen subjects aged 20-39 years were enrolled in the study. Refractive state and accommodation were measured using an open-field autorefractor with three target vergences, namely, -0.20 D, -2.5 D, and -4.0 D. Binocular visual acuity at high (100%) and low (40%, 20%) contrast and reading ability were assessed. Monofocal soft CLs were used as controls.

RESULTS

Accommodative response with low-add CLs was significantly smaller than those with two monofocal CL wearing conditions, i.e., at 40 cm (2.5 D of stimulus) and 25 cm (4.0 D of stimulus) (all p < 0.05). The 20% contrast visual acuity at distance was significantly better with low-add CLs and second-time monofocal CLs compared to first-time monofocal CLs (all p < 0.05). The reading ability was not significantly different.

CONCLUSIONS

Quantification of accommodative response and visual performance demonstrated that using low-add CLs alleviated the accommodation under the near-vision condition, without sacrificing distance vision, in non-presbyopes.

Visual implications of digital device usage in school children: a cross-sectional study

PURPOSE

To evaluate the use of digital devices, reading habits and the prevalence of eyestrain among urban Indian school children, aged 11-17 years.

METHODS

The study included 576 adolescents attending urban schools who were surveyed regarding their electronic device usage. Additional information on the factors that may have an effect on ocular symptoms was collected.

RESULTS

Twenty percent of students aged 11 in the study population use digital devices on a daily basis, in comparison with 50% of students aged 17. In addition to using these devices as homework aids, one third of study participants reported using digital devices for reading instead of conventional textbooks. The majority of students preferred sitting on a chair while reading (77%; 445 students), with only 21% (123 students) preferring to lie on the bed and 8 students alternating between chair and bed. There was a significant association between the students who preferred to lie down and those who experienced eyestrain, as reported by a little over one fourth of the student population (27%). Out of 576 students, 18% (103) experienced eyestrain at the end of the day after working on digital devices.

CONCLUSIONS

The increased use of digital devices by adolescents brings a new challenge of digital eyestrain at an early age. Our study reports the patterns of electronic device usage by school children, evaluates factors associated with eyestrain and highlights the need for further investigation of these issues.

Binocular coordination and reading performance during smartphone reading in intermittent exotropia

Purpose

This study aimed to evaluate binocular coordination using video-oculography during smartphone reading in patients with intermittent exotropia compared to individuals with normal vision.

Patients and methods

Eleven youth and adult patients with intermittent exotropia (21.9±9.3 years) and 15 control subjects (26.6±4.3 years) were examined. Eye movements were recorded during smartphone reading at 50, 30, and 20 cm using video-oculography. The loss of binocular coordination was tentatively defined as a horizontal disparity greater than 2°. The proportion of monocular viewing was the percentage of time for which binocularity was lost during smartphone reading. The proportion of monocular viewing, the reading speed, and the correlation between proportion of monocular viewing and reading speed were analyzed.

Results

The proportion of monocular viewing during smartphone reading was significantly higher in the intermittent exotropia group than in the control group (P<0.001). It was significantly more frequent at 20 cm than at 50 cm in the intermittent exotropia group (P<0.05). The reading speed was significantly negatively correlated with the proportion of monocular viewing at 30 and 20 cm in the intermittent exotropia group (P<0.05).

Conclusion

A significant increase in the proportion of monocular viewing in the intermittent exotropia group suggests that an appropriate viewing distance should be advised so that users can maintain binocular coordination when viewing a smartphone.

Associations between problematic Internet use and psychiatric symptoms among university students in Japan

AIM

Research on the adverse effects of Internet use has gained importance recently. However, there is currently insufficient data on Japanese young adults' Internet use, so we conducted a survey targeting Japanese university students to research problematic Internet use (PIU). We also investigated the relationship between PIU and multiple psychiatric symptoms.

METHODS

A paper-based survey was conducted at five universities in Japan. Respondents were asked to fill out self-report scales regarding their Internet dependency using the Internet Addiction Test (IAT). Sleep quality, attention-deficit hyperactivity disorder (ADHD) tendency, depression, and anxiety symptom data were also collected based on respective self-reports.

RESULTS

There were 1336 responses and 1258 were included in the analysis. The mean IAT score (± SD) was 37.87 ± 12.59; and 38.2% of participants were classified as PIU, and 61.8% as non-PIU. The trend level for young women showed that they were more likely to be classified as PIU than young men (40.6% and 35.2% respectively, P = 0.05). Compared to the non-PIU group, the PIU group used the Internet longer (P < 0.001), had significantly lower sleep quality (P < 0.001), had stronger ADHD tendencies (P < 0.001), had higher Depression scores (P < 0.001), and had higher Trait-Anxiety scores (P < 0.001). Based on multiple logistic regression analyses, the factors that contributed to an increased risk of PIU were: being female (odds ratio [OR] = 1.52), being older (OR = 1.17), having poor sleep quality (OR = 1.52), having ADHD tendencies (OR = 2.70), having depression (OR = 2.24), and having anxiety tendencies (OR = 1.43).

CONCLUSION

We found a high PIU prevalence among Japanese young adults. The factors that predicted PIU were: female sex, older age, poor sleep quality, ADHD tendencies, depression, and anxiety.

The potential influence of LED lighting on mental illness

OBJECTIVES

Two recent scientific breakthroughs may alter the treatment of mental illness, as discussed in this narrative review. The first was the invention of white light-emitting diodes (LEDs), which enabled an ongoing, rapid transition to energy-efficient LEDs for lighting, and the use of LEDs to backlight digital devices. The second was the discovery of melanopsin-expressing photosensitive retinal ganglion cells, which detect environmental irradiance and mediate non-image forming (NIF) functions including circadian entrainment, melatonin secretion, alertness, sleep regulation and the pupillary light reflex. These two breakthroughs are interrelated because unlike conventional lighting, white LEDs have a dominant spectral wavelength in the blue light range, near the peak sensitivity for the melanopsin system.

METHODS

Pertinent articles were identified.

RESULTS

Blue light exposure may suppress melatonin, increase alertness, and interfere with sleep in young, healthy volunteers and in animals. Areas of concern in mental illness include the influence of blue light on sleep, other circadian-mediated symptoms, prescribed treatments that target the circadian system, measurement using digital apps and devices, and adolescent sensitivity to blue light.

CONCLUSIONS

While knowledge in both fields is expanding rapidly, future developments must address the potential impact of blue light on NIF functions for healthy individuals and those with mental illness.