The association between shift work, shift work sleep disorders and premature ejaculation in male workers.

OBJECTIVE: Shift work and Shift Work Sleep Disorder (SWSD) are known to affect the secretion of several neurotransmitters and hormones associated with premature ejaculation (PE). However, their specific influence on the regulation of male ejaculation remains unclear. This study explores the relationship between shift work, SWSD, and PE. METHODS: From April to October 2023, a cross-sectional survey was conducted across five regions of China to explore the work schedules, sleep quality, and sexual function of male workers. Participants' sleep quality was evaluated using a validated SWSD questionnaire, and their erectile function and ejaculatory control were assessed with the International Inventory of Erectile Function (IIEF-5) scores and Premature Ejaculation Diagnostic Tool (PEDT) scores, respectively. Univariate and multivariate linear regression analyses were employed to identify risk factors associated with PE. Confounders were controlled using multiple regression models, and clinical prediction models were developed to predict PE onset and assess the contribution of risk factors. RESULTS: The study included 1239 eligible participants, comprising 840 non-shift workers and 399 shift workers (148 with SWSD and 251 without SWSD). Compared to non-shift working males, those involved in shift work (ß 1.58, 95% CI 0.75 - 2.42, p < 0.001) and those suffering from SWSD (ß 2.86, 95% CI 1.86 - 3.85, p < 0.001) they had significantly higher PEDT scores. Additionally, we identified daily sleep of less than six hours, depression, anxiety, diabetes, hyperlipidemia, frequent alcohol consumption (more than twice a week), and erectile dysfunction as risk factors for PE. The predictive model for PE demonstrated commendable efficacy. CONCLUSION: Both shift work and SWSD significantly increase the risk of premature ejaculation, with the risk magnifying in tandem with the duration of shift work. This study reveals the potential impact of shift work and SWSD on PE and provides new theoretical foundations for the risk assessment and prevention of this condition.

Circadian Disruption in Civilian Airline Pilots.

INTRODUCTION: Most airline pilots reported having suffered from sleep disorders and fatigue due to circadian disruption, a potential risk to flight safety. This study attempted to uncover the actual scenario of circadian disruption and working load status among airline pilots.METHODS: In study 1, 21 pilots were invited to participate in a 14-d sleep monitoring and a dual 2-back test to monitor their sleep patterns and cognitive function level. To provide an in-depth view, data from scheduled flights, including 567 airline pilots, was analyzed in Study 2. The present study used cluster analysis to reflect the distribution of the flight scheduling characteristics, including working time and actual working hours. A simulation model was then developed to predict the pilots' 1-mo sleep-wake pattern.RESULTS: The results indicated that sleep problems were prevalent in this population, especially the night before an earlier morning shift. Regarding the cognitive test, they scored the lowest on earlier morning shifts compared with daytime and evening shifts. It was found that over 70% of the flight schedules can lead to circadian disruption, and 47.44% of the pilots worked under high-load status.DISCUSSION: Airline pilots inevitably work irregular hours and the current policies for coping with circadian disruption seem inefficient. This study thus calls for urgency in improving scheduling and fatigue management systems from the circadian rhythm perspective.Yang SX, Cheng S, Sun Y, Tang X, Huang Z. Circadian disruption in civilian airline pilots. Aerosp Med Hum Perform. 2024; 95(7):381-389.

Light, sleep and circadian rhythm in critical illness.

PURPOSE OF REVIEW: Sleep and circadian disruption (SCD) are associated with worse outcomes in the ICU population. We discuss sleep, circadian physiology, the role of light in circadian entrainment and its possible role in treating SCD, with special attention to the use of light therapies and ICU design. RECENT FINDINGS: The American Thoracic Society recently published an official research statement highlighting key areas required to define and treat ICU SCD. Recent literature has been predominantly observational, describing how both critical illness and the ICU environment might impair normal sleep and impact circadian rhythm. Emerging consensus guidance outlines the need for standardized light metrics in clinical trials investigating effects of light therapies. A recent proof-of-concept randomized controlled trial (RCT) showed improvement in delirium incidence and circadian alignment from ICU room redesign that included a dynamic lighting system (DLS). SUMMARY: Further investigation is needed to define the optimal physical properties of light therapy in the ICU environment as well as timing and duration of light treatments. Work in this area will inform future circadian-promoting design, as well as multicomponent nonpharmacological protocols, to mitigate ICU SCD with the objective of improving patient outcomes.

Assessment and management of sleep disorders in shift workers: Challenges and considerations for general practice.

BACKGROUND: Shift work is characterised by displaced sleep opportunities and associated sleep disturbance. Shift workers often report sleepiness and other wake time symptoms associated with poor sleep. However, clinical sleep disorders are also prevalent in shift workers. Although prevalence rates are similar or higher in shift workers compared with the general population, help seeking in shift workers with sleep disorders is low. OBJECTIVE: This article aims to provide general practitioners with a contemporary overview of the prevalence rates for sleep disorders in shift workers, to clarify the existing evidence relating to mental and physical health consequences of sleep disorders in shift workers and to highlight the need to consider undiagnosed sleep disorders before attributing sleep-related symptoms solely to work schedules. DISCUSSION: Symptoms of sleep loss associated with shift work overlap with symptoms experienced by individuals living with sleep disorders. Although >40% of middle-aged Australians live with a sleep disorder that requires investigation and management, symptoms in shift workers are often attributed to the work schedule and, as a result, might not be investigated for appropriate diagnosis and treatment. We argue that screening for sleep disorders in shift workers with sleep complaints should be a priority.

Moderating effect of shift work on sleep and depression in individuals at high risk of bipolar disorder.

BACKGROUND: Social Zeitgeber Theory posits that disruptions in social rhythms can increase susceptibility to bipolar disorder (BD). Shift work (SW) is one of the external factors that cause instability in social rhythms and the sleep-wake cycle. This study evaluated the moderating influences of SW on the risks of BD and sleep-related parameters and depressive symptoms. Furthermore, we evaluated the specific work schedules including daytime, nighttime, and regular and irregular rotating SW. METHODS: An online survey was administered to 6665 participants, with 3379 (50.7 %) classified as individuals with high scores of Mood Disorder Questionnaire (MDQ). The survey included the Pittsburgh Sleep Quality Index (PSQI), Insomnia Severity Scale (ISI), Epworth Sleepiness Scale (ESS), and Center for Epidemiologic Studies Depression Scale (CES-D). RESULTS: A multivariate regression model revealed significant interactive effects of MDQ positivity and SW on PSQI, ISI, and CES-D scores, but not ESS scores. In a secondary analysis of the high MDQ screen group, daytime workers had lower scores in sleep disturbances and depressive symptoms compared to those engaged in other forms of SW. LIMITATIONS: Online surveys were accessible voluntarily, leading to potential selection bias. Cross-sectional data identified associations, not causal relationships. Only a self-reported questionnaire was used. CONCLUSIONS: Our findings emphasize the advantages of a daytime work schedule for individuals at high risk of BD. In accordance with the principles of social rhythm interpersonal therapy, sleep interventions for individuals at high risk of BD should include the maintenance of a consistent daytime schedule.

Prevalence, correlates, and mental health outcomes of social jetlag in Chinese school-age adolescents: A large-scale population-based study.

BACKGROUND: This cross-sectional study aimed to examine the prevalence and correlates of social jetlag (SJL) in Chinese adolescents, as well as to test the relationships between SJL and mental health problems. METHODS: A total of 106979 students (Mage = 13.0 ± 1.8 years; Nmale = 58296 [54.5 %]) from Shenzhen, China completed an online survey from May 24th to June 5th, 2022. Information on sociodemographics, lifestyles, sleep characteristics, anxiety symptoms, and depressive symptoms was collected by a self-administered questionnaire. Multivariate and binary logistic regression were adopted for data analysis. RESULTS: 17.8 % of participants experienced SJL ≥ 2 h. To adjust the accumulated sleep debt, sleep-corrected SJL (SJLsc) was calculated and 8.3 % of individuals self-reported SJLsc ≥ 2 h. Both SJL and SJLsc show an increasing trend with age. Risk factors of SJL included females, poor parental marital status, being overweight, physically inactive, smoking, drinking, and having a late chronotype. Moreover, males, having siblings, boarding at school, short sleep duration, experiencing insomnia, and frequent nightmares were significantly associated with an increased risk of SJLsc. After adjusting for all covariates, adolescents with SJLsc ≥ 2 h were more likely to have anxiety symptoms (OR: 1.35, 95 % CI: 1.24-1.48) and depressive symptoms (OR: 1.35, 95 % CI: 1.25-1.46) than those with SJLsc < 1 h. CONCLUSIONS: SJL is common among Chinese school-age adolescents. This study is valuable for the development of prevention and intervention strategies for SJL in adolescents at the population level. Additionally, the strong links between SJLsc and emotional problems underscore the critical significance of addressing SJL as a key aspect of adolescent well-being.

The use of prolonged-release melatonin in circadian medicine: a systematic review.

INTRODUCTION: Melatonin, a hormone produced by the pineal gland, regulates the sleep-wake cycle and is effective in restoring biological rhythms. Prolonged-release melatonin (PRM) is designed to mimic the natural physiological pattern of melatonin release. In circadian medicine, PRM can be used to treat sleep and circadian rhythm disorders, as well as numerous organic diseases associated with sleep disorders. EVIDENCE ACQUISITION: This systematic review analyzed 62 studies and adhered to the PRISMA guidelines, examining the effectiveness of PRM in organic pathologies and mental disorders. EVIDENCE SYNTHESIS: The main evidence concerns primary insomnia in subjects over the age of 55, showing significant improvements in sleep quality. In neurodevelopmental disorders, there is evidence of a positive impact on sleep quality and quality of life for patients and their caregivers. PRM shows efficacy in the treatment of sleep disorders in mood disorders, schizophrenia, and neurocognitive disorders, but requires further confirmation. The additional use of PRM is supported for the withdrawal of chronic benzodiazepine therapies. The tolerability and safety of PRM are excellent, with ample evidence supporting the absence of tolerance and dependence. CONCLUSIONS: Overall, PRM in circadian medicine is an effective chronopharmaceutical for restoring the sleep-wake rhythm in patients with insomnia disorder. This efficacy may also extend to sleep disorders associated with mood, neurodevelopmental and neurocognitive disorders, suggesting a further potential role in insomnia associated with various organic diseases.

Variants in the circadian clock genes PER2 and PER3 associate with familial sleep phase disorders.

Delayed sleep phase disorder and advanced sleep phase disorder cause disruption of the circadian clock and present with extreme morning/evening chronotype with unclear role of the genetic etiology, especially for delayed sleep phase disorder. To assess if genotyping can aid in clinical diagnosis, we examined the presence of genetic variants in circadian clock genes previously linked to both sleep disorders in Slovenian patient cohort. Based on Morning-evening questionnaire, we found 15 patients with extreme chronotypes, 13 evening and 2 morning, and 28 controls. Sanger sequencing was used to determine the presence of carefully selected candidate SNPs in regions of the CSNK1D, PER2/3 and CRY1 genes. In a patient with an extreme morning chronotype and a family history of circadian sleep disorder we identified two heterozygous missense variants in PER3 gene, c.1243C>G (NM_001377275.1 (p.Pro415Ala)) and c.1250A>G (NM_001377275.1 (p.His417Arg)). The variants were significantly linked to Advanced sleep phase disorder and were also found in proband's father with extreme morningness. Additionally, a rare SNP was found in PER2 gene in a patient with clinical picture of Delayed sleep phase disorder. The novel variant in PER2 (NM_022817.3):c.1901-218 G>T was found in proband's parent with eveningness, indicating an autosomal dominant inheritance. We identified a family with autosomal dominant inheritance of two PER3 heterozygous variants that can be linked to Advanced sleep phase disorder. We revealed also a rare hereditary form of Delayed sleep phase disorder with a new PER2 variant with autosomal dominant inheritance, shedding the light into the genetic causality.

Sleep, mental health and physical health in new shift workers transitioning to shift work: Systematic review and meta-analysis.

This systematic review and meta-analysis (PROSPERO registration CRD42022309827) aimed to describe how shift work impacts new workers' sleep, mental health, and physical health during the transition to shift work and to consolidate information regarding predictors of shift work tolerance (SWT) during this transition period. Inclusion criteria included: new shift workers; sleep, mental health, or physical health outcomes; prospective study design with the first timepoint assessing workers within three months of starting shift work; and written in English. Searches from six databases returned 12,172 articles as of August 2023. The final sample included 48 papers. Publication quality and risk of bias was assessed using the critical appraisal skills program. Forty-five studies investigated longitudinal changes in sleep, mental health, or physical health outcomes and 29 studies investigated predictors of SWT (i.e., better sleep, mental and physical health). Sleep and mental health outcomes worsened following the onset of shift work, while physical health did not significantly change. Pre-shift work mental health, sleep, and work characteristics predicted SWT later in workers' careers. Shift work adversely impacts new workers' sleep and mental health early in their career, and interventions before beginning shift work are needed to promote better SWT.

Effects of cognitive behavioural therapy and bright light therapy for insomnia in youths with eveningness: study protocol for a randomised controlled trial.

BACKGROUND: Insomnia and eveningness are common and often comorbid conditions in youths. While cognitive behavioural therapy for insomnia (CBT-I) has been suggested as a promising intervention, it remains unclear whether it is sufficient to also address circadian issues in youths. In addition, despite that light has been shown to be effective in phase-shifting one's circadian rhythm, there has been limited data on the effects of bright light therapy and its combination with CBT-I on sleep and circadian outcomes in youths. The current protocol outlines a randomised controlled trial that examines the efficacy of CBT-I and CBT-I plus bright light therapy (BLT) in reducing insomnia severity, improving mood symptoms and daytime functioning (e.g. sleepiness, fatigue, cognitive function), and improving subjective and objective sleep and circadian measures compared to a waitlist control group. METHODS: We will carry out a randomised controlled trial (RCT) with 150 youths aged 12-24 who meet the criteria of insomnia and eveningness. Participants will be randomised into one of three groups: CBT-I with bright light therapy, CBT-I with placebo light, and waitlist control. Six sessions of CBT-I will be delivered in a group format, while participants will be currently asked to use a portable light device for 30 min daily immediately after awakening throughout the intervention period for bright light therapy. The CBT-I with light therapy group will receive bright constant green light (506 lx) while the CBT-I with placebo light group will receive the modified light device with the LEDs emitting less than 10 lx. All participants will be assessed at baseline and post-treatment, while the two active treatment groups will be additionally followed up at 1 month and 6 months post-intervention. The primary outcome will be insomnia severity, as measured by the Insomnia Severity Index. Secondary outcomes include self-reported mood, circadian, daytime functioning, and quality of life measures, as well as sleep parameters derived from actigraphy and sleep diary and neurocognitive assessments. Objective measures of the circadian phase using dim-light melatonin onset assessment and sleep parameters using polysomnography will also be included as the secondary outcomes. DISCUSSION: This study will be the first RCT to directly compare the effects of CBT-I and BLT in youths with insomnia and eveningness. Findings from the study will provide evidence to inform the clinical management of insomnia problems and eveningness in youths. TRIAL REGISTRATION: ClinicalTrials.gov NCT04256915. Registered on 5 February 2020.

Low-dose exogenous melatonin plus evening dim light and time in bed scheduling advances circadian phase irrespective of measured or estimated dim light melatonin onset time: preliminary findings.

STUDY OBJECTIVES: The purpose of the present study was to preliminarily evaluate whether knowing the dim light melatonin onset (DLMO) time is advantageous when treating delayed sleep-wake phase disorder with low-dose melatonin treatment plus behavioral interventions (ie, evening dim light and time in bed scheduling). METHODS: In this randomized, controlled, double-blind trial, 40 adults with delayed sleep-wake phase disorder were randomly assigned to 4 weeks of 0.5 mg timed to be administered either 3 hours before the DLMO (measured DLMO group, n = 20) or 5 hours before sleep-onset time per actigraphy (estimated DLMO group, n = 20), in conjunction with behavioral interventions. The primary outcome was change in the DLMO (measured in-home). Secondary outcomes included sleep parameters per diary and actigraphy (sleep-onset and -offset times and total sleep time), Morningness-Eveningness Questionnaire, Multidimensional Fatigue Inventory, PROMIS-Sleep Disturbance, PROMIS-Sleep Related Impairment, and Pittsburgh Sleep Quality Index. Mixed-effects models tested for group differences in these outcome. RESULTS: After applying the Bonferroni correction for multiple comparisons (significant P value set at < .004), there were significant main effects for visit on all outcomes except for the Pittsburgh Sleep Quality Index and total sleep time per wrist actigraphy and diary. There were no group-by-visit interactions for any of the outcomes (P > .004). CONCLUSIONS: Scheduled low-dose melatonin plus behavioral interventions may improve many circadian and sleep parameters regardless of whether melatonin administration is scheduled based on estimated or measured DLMO. A larger-scale trial is needed to confirm these preliminary findings. CLINICAL TRIAL REGISTRATION: Registry: ClinicalTrials.gov; Name: The Clinical Utility of Measuring the Circadian Clock in Treatment of Delayed Sleep-Wake Phase Disorder; URL: https://clinicaltrials.gov/study/NCT03715465; Identifier: NCT03715465. CITATION: Swanson LM, de Sibour T, DuBuc K, et al. Low-dose exogenous melatonin plus evening dim light and time in bed scheduling advances circadian phase irrespective of measured or estimated dim light melatonin onset time: preliminary findings. J Clin Sleep Med. 2024;20(7):1131-1140.

Shift Work Sleep Disorder and Mental Health: An Integrative Review of Neurobiological, Sociological, and Psychological Perspectives With Public Policy Implications.

Shift workers support critical 24-hr operations; their health can be impaired by disrupted circadian rhythms and dysfunctional sleep. Shift work sleep disorder (SWSD) is a prevalent condition with significant psychological consequences. Nurse leaders have not yet implemented effective policies to prevent SWSD and optimize shift workers' mental health. The purpose of this integrative review was to examine research about SWSD within the context of neurobiological, sociological, and psychological perspectives that can inform policy changes. The Centers for Disease Control and Prevention Policy Analytic Framework was used to determine the priority recommendations. A search of three databases provided 19 research articles about SWSD and mental health, which illustrated how SWSD is common around the world in many occupations. Backward-rotating schedules and quick returns were risk factors for SWSD. In addition, SWSD was associated with circadian languidity, sleep reactivity, depressive symptoms, and anxiety. Collectively, the studies lacked objective measures of sleep and circadian rhythms, which has hindered the ability to devise interventions that will target the neurobiological causes of SWSD. The research also lacked attention to important sociological factors, such as workers' pay and benefits. Using these findings, nurse leaders can contribute to public policy reforms that increase funding for more rigorous SWSD research. Lawmakers should be advised by nurse leaders to enforce new regulations that provide incentives for employers to create healthier workplaces, such as prohibiting the overuse of schedules that make employees vulnerable to SWSD and providing funds for interventions to prevent SWSD and support mental health.

Sex Differences in Insomnia and Circadian Rhythm Disorders: A Systematic Review.

Insomnia and circadian rhythm disorders are increasingly common in modern society and lead to significant challenges for people's health and well-being. Some studies suggests that men and women differ in neurohormonal secretion, biological processes, and brain morphology. Thus, such differences may affect the etiology, manifestation, and course of sleep disorders, including insomnia and circadian rhythm. This systematic review aims to synthesize the existing literature on sex differences in insomnia and circadian rhythm disorders. PubMed, MEDLINE, Epistemonikos, and Cochrane databases were searched for articles published from inception until 5 September 2023, not older than five years. We performed a systematic search using MESH and non-MESH queries: (sex differences) or (male and female differences) or (men and women differences) or (men and women) AND (insomnia) or (sleep wake disorder*) or (sleep wake rhythm disorder*) or (circadian rhythm disorder*) or (sleep cycle disruption) or (sleep cycle disorder*). Out off 2833 articles screened, 11 studies were included. The prevalence of insomnia is higher among women, and their sleep is more regular and stable compared to men. Studies evaluating the impact of the stressful situation associated with the lockdown on women's and men's insomnia present discordant results concerning sex differences. Women's circadian rhythm was found to be more stable and less fragmented than men's. However, the progression of peak activity time with age was more pronounced in men. The current literature suggests that risk factors for insomnia and circadian rhythm disorders affect men and women differently. These include cerebrovascular and cardiometabolic factors, shift work, and infections. The long-term effects of insomnia seem to be more relevant for the male sex, shortening lifespan more than in women. By summarizing and analyzing existing studies, we highlight the need for further research to improve understanding of the interaction between sex and sleep.

Images: "Too much heat for my non-24-hour sleep-wake disorder!" A case report.

The non-24-hour sleep-wake disorder (N24SWD) is a rare condition, sometimes associated with blindness or with suprachiasmatic nuclei lesions, resulting in a free-running rhythm or hypernycthemeral syndrome. Synchronizers, such as light, when light perception remains, melatonin, food intakes, physical activity, social interactions, and temperature, play a key role in the treatment of N24SWD. In this report, we describe a case illustrating the impact of outdoor temperature in a 34-year-old man with N24SWD effectively treated through a combination of chronotherapy interventions. During 3 consecutive heat waves, he experienced a recurrence of his natural 25.5-hour free-running rhythm, with a consistent bedtime phase delay caused by temperature, resulting in the discontinuation of chronotherapy. After these heat waves, he was able again to resynchronize his rhythms with the combination of chronotherapeutics. This case report highlights that patients with N24SWD may be particularly at risk of relapse during heat waves, with direct implications for monitoring and reinforcing chronotherapies. CITATION: Garrivet J, d'Ortho M-P, Frija-Masson J, et al. "Too much heat for my non-24-hour sleep-wake disorder!" A case report. J Clin Sleep Med. 2024;20(2):329-333.

Just Let Me Sleep in: Identifying and Treating Delayed Sleep Phase Disorder in Adolescents.

Individuals with delayed sleep phase disorder (DSPD) are unable to naturally fall asleep and awake at conventional times; for this reason, DSPD is often mistaken for insomnia. However, unlike many patients with insomnia, those with DSPD struggle to get up at appropriate times. DSPD is associated with school refusal, academic difficulties, and lower employment rate. DSPD in youth has prevalence as high as 16%, and is often comorbid with other psychiatric disorders. Treatments include appropriate light exposure during the day, melatonin use, developing an evening routine that minimizes arousal-increasing activities, and gradually shifting sleep-wake times toward more functional ones.

Managing non-24-hour sleep-wake rhythm disorder with ramelteon in a 12-year-old girl with Pierre Robin sequence and developmental delay: a case report.

The author recently observed a case involving a 12-year-old sighted girl who exhibited symptoms typical of non-24-hour sleep-wake rhythm disorder (N24SWD). This disorder, more commonly found in blind individuals, presents a unique challenge when diagnosed in those with vision. Several interventions can be attempted, ranging from behavioral adjustments to light therapy. Although melatonin has been noted for its effectiveness in realigning the patient's sleep-wake cycle, the use of ramelteon, a melatonin receptor agonist, has seldom been reported in managing N24SWD. However, this case illuminates the potential of ramelteon as another therapeutic option for sighted individuals with N24SWD. Further study is suggested to determine the potential of ramelteon in managing this disorder among sighted individuals of varying age groups. CITATION: Huang C-H. Managing non-24-hour sleep-wake rhythm disorder with ramelteon in a 12-year-old girl with Pierre Robin sequence and developmental delay: a case report. J Clin Sleep Med. 2024;20(6):995-997.

Improvement in non-24-h sleep-wake rhythm disorder in a sighted individual treated with a melatonin receptor agonist.

Non-24-hour sleep-wake rhythm disorder (N24SWD) typically presents in patients with visual impairments that disrupt the ability to entrain to the 24 hour solar cycle. We discuss a 43 year old sighted man who presented with periodic daytime hypersomnia and nighttime insomnia, occasionally leading to <3 hours of sleep per day. Previous polysomnography showed an apnea hypopnea index of 6.2 events per hour. A sleep log of 3 months showed irregular time of sleep onset, and an average of 3 hours of sleep per day. Wrist actigraphy confirmed N24SWD. A trial of tasimelteon 20 mg/day resulting in improved daytime hypersomnia (pre-Epworth Sleepiness Scale (ESS) = 21/24, post-ESS = 5/24; a score of > 10/24 is considered sleepy). Follow-up actigraphy showed marked resolution of phase delay with an average of five hours of sleep. The case demonstrates that tasimelteon is a possible treatment for N24SWD in sighted individuals.

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.