Karolinska Sleepiness Scale Scores Research Articles

Development of sleepiness in professional truck drivers: Real-road testing for driver drowsiness and attention warning (DDAW) system evaluation.

All new vehicle types within the European Union must now be equipped with a driver drowsiness and attention warning system starting from 2022. The specific requirements for the test procedure necessary for type approval are defined in the Annex of EU Regulation C/2021/2639. The objectives of this study were to: (i) investigate how sleepiness develops in professional truck drivers under real-road driving conditions; and (ii) assess the feasibility of a test procedure for validating driver drowsiness and attention warning systems according to the EU regulation. Twenty-four professional truck drivers participated in the test. They drove for 180 km on a dual-lane motorway, first during daytime after a normal night's sleep and then at nighttime after being awake since early morning. The results showed higher sleepiness levels during nighttime driving compared with daytime, with a faster increase in sleepiness with distance driven, especially during the night. Psychomotor vigilance task results corroborated these findings. From a driver drowsiness and attention warning testing perspective, the study design with sleep-deprived drivers at night was successful in inducing the targeted sleepiness level of a Karolinska Sleepiness Scale score of ≥ 8. Many drivers who reported a Karolinska Sleepiness Scale ≥ 8 during the drives also acknowledged feeling sleepy in the post-drive questionnaire. Reaching high levels of sleepiness on real roads during daytime is more problematic, not the least from legal and ethical perspectives as higher traffic densities during the daytime lead to increased risks.

Sleep and subjective age: protect your sleep if you want to feel young.

The current studies examined the impact of insufficient sleep and sleepiness on the subjective experience of age. Study 1, a cross-sectional study of 429 participants (282 females (66%), 144 males, 3 other gender; age range 18-70), showed that for each additional day of insufficient sleep in the last 30 days, subjective age increased by 0.23 years. Study 2, an experimental crossover sleep restriction study (n = 186; 102 females (55%), 84 males; age range 18-46), showed that two nights of sleep restriction (4 h in bed per night) made people feel 4.44 years older compared to sleep saturation (9 h in bed per night). Additionally, moving from feeling extremely alert (Karolinska Sleepiness Scale (KSS) score of 1) to feeling extremely sleepy (KSS score of 9) was associated with feeling 10 years older in both studies. These findings provide compelling support for insufficient sleep and sleepiness to exert a substantial influence on how old we feel, and that safeguarding sleep is probably a key factor in feeling young.

The evaluation of cEEGrids for fatigue detection in aviation.

Operator fatigue poses a major concern in safety-critical industries such as aviation, potentially increasing the chances of errors and accidents. To better understand this risk, there is a need for noninvasive objective measures of fatigue. This study aimed to evaluate the performance of cEEGrids, a type of ear-EEG, for fatigue detection by analyzing the alpha and theta power before and after sleep restriction in four sessions on two separate days, employing a within-participants design. Results were compared to traditional, highly validated methods: the Karolinska Sleepiness Scale (KSS) and Psychomotor Vigilance Task (PVT). After sleep restriction and an office workday, 12 participants showed increased alpha band power in multiple electrode channels, but no channels correlated with KSS scores and PVT response speed. These findings indicate that cEEGrids can detect differences in alpha power following mild sleep loss. However, it should be noted that this capability was limited to specific channels, and no difference in theta power was observed. The study shows the potential and limitations of ear-EEG for fatigue detection as a less invasive alternative to cap-EEG. Further design and electrode configuration adjustments are necessary before ear-EEG can be implemented for fatigue detection in the field.

Ad libitum caffeine consumption, cognitive performance, and sleep in special forces soldiers during a 96-h combat exercise.

This observational study investigated the effects of sleep deprivation and ad libitum caffeine consumption on cognitive performance, risk behavior, and mood among 28 Israeli Special Forces (SF) soldiers (mean age: 20.57 ± 0.92 years) during a 96-hour combat exercise. Actigraphy was used to monitor sleep and activity; cognitive function, risk-taking propensity, mood states, and self-reported sleepiness were assessed using the Psychomotor Vigilance Task (PVT), Evaluation of Risks Scale (EVAR), Profile of Mood States (POMS), Karolinska Sleepiness Scale (KSS); and caffeine consumption by questionnaire at 0, 50, and 96 hours. For analyses, participants were divided into Low (<400 mg) and High (≥400 mg) caffeine consumption groups. The soldiers hiked 108.5 ± 0.52 km and slept for 12.7 ± 0.5 h, with a notable transition from multiple short sleep epochs in the initial 50 hours to a consolidated 5-hour sleep period subsequently. In the High caffeine group, PVT reaction time was faster (p = 0.024) compared to the Low caffeine group, with fewer premature response errors (p = 0.026). However, this group showed increased risk-taking (p = 0.037), particularly reduced Self-Control (p = 0.010). No significant impact of ad libitum caffeine intake on mood was observed. However, degradation over the course of the exercise in both groups in mood states, including anger, fatigue, tension, and vigor, was noted (p < 0.05). KSS scores increased significantly at 50 and 96 h (p < 0.001). These results suggest that while caffeine enhances cognitive function, its ad libitum consumption did not consistently improve these measures in this cohort of SF soldiers. The study highlights the complex relationship between sleep deprivation and caffeine intake and their combined effects on soldiers' cognitive and behavioral functions, indicating a need for evidence-based caffeine use guidelines for using caffeine in military settings.

Effects of a simulated maritime shift schedule on vigilance, sleep, and sleepiness

ABSTRACT Shift work is associated with circadian misalignment, which causes sleep loss, impairs performance, and increases the risk of accidents. Shorter, more frequently shifting watch schedules, widely used in industries such as maritime operation, defense, and mining, may mitigate these risks by reducing shift length and providing sleep opportunities for all workers across the biological night. However, the effects of frequently shifting work on sleep and performance still need to be clarified. The current study investigated the vigilance, sleepiness, and sleep patterns of fifteen participants who lived in a controlled and confined laboratory that mimicked a maritime environment for 14 d following a simulating frequent shift schedule. The results of psychomotor vigilance tasks (PVT) suggest that this shift schedule may lead to an accumulation of vigilance detrimental across watch days, with both reaction speed impairment and error growth. Furthermore, the circadian phase significantly affects PVT performance, with the afternoon shift section showing relatively better performance. Overall, more working hours per day resulted in poorer PVT performance. As the shift progressed, total sleep duration reduced slightly, and wake after sleep onset (WASO) increased. Sleep during the biological night was generally longer than sleep in the daytime. Less on-watch time was linked to longer overall sleep duration. Additionally, although the subjective sleepiness obtained by the Karolinska Sleepiness Scale (KSS) varied insignificantly across days, the KSS score was negatively correlated with PVT performance. This research can serve as a foundation for developing countermeasures to mitigate frequently shifting schedules’ potentially detrimental effects and safety risks.

Karolinska Sleepiness Scale is not Associated with Obstructive Sleep Apnea Severity Indices in Male Taxi Drivers

Objective: In the current study, we aimed to evaluate the diagnostic utility of the Karolinska Sleepiness Scale (KSS) for obstructive sleep apnea (OSA) in taxi drivers. Methods: Forty male professional taxi drivers who participated in a driving simulator experiment in the sleep laboratory were included in the current study. All participants were asked to fill out the KSS before and after a 50-minute driving simulator task in the morning after overnight polysomnography (PSG) in the hospital. OSA was defined as an apnea-hypopnea-index (AHI) 15 events/hour on the PSG. Excessive daytime sleepiness (EDS) was defined as KSS score of at least 6. Results: In all, only 3 cases fulfilled the criteria for EDS before the driving whereas 13 cases were sleepy after the task was completed (p &lt;0.001). No significant association was found between KSS scores after the task and the PSG variables including total sleep time, time spent in delta sleep and REM sleep as well as OSA severity indices AHI and Oxygen Desaturation Index (ODI). The agreement between OSA and sleepiness on the KSS was calculated as 0.21 (p=0.07) indicating a very weak association. The KSS has a sensitivity of 24.1%, a specificity of 45.5%, a positive predictive value of 53.9%, a negative predictive value of 30.0%, an accuracy of 46.6% for the OSA diagnosis. The area under the curve was 0.57 (95% CI 0.39 – 0.74) for the AHI and 0.56 (95% CI 0.39 – 0.73) for the ODI, confirming a very poor performance of the KSS scores to predict AHI and ODI. Conclusion: The KSS is not associated with the severity of the OSA indices in male taxi drivers. Objective measurements of EDS are warranted for a more precise evaluation of fitness to drive in professional drivers.

Effects of red light on sleep and mood in healthy subjects and individuals with insomnia disorder.

This study aimed to determine the influence of red light on objective sleep and the relationship between mood and sleep among individuals with insomnia disorder (ID). 57 individuals with insomnia symptoms and 57 healthy participants were randomly divided into three groups (red- and white-light groups, and the black control group), which received different light treatments for 1 h before bedtime. The emotions and subjective alertness of participants were evaluated using Positive and Negative Affect Schedule scales (PANAS) and Karolinska Sleepiness Scale (KSS), their sleeping data were recorded using polysomnography (PSG). The negative emotion scores were higher in the healthy subject-red light (HS-RL) group than in the HS-white light (WL) and HS-black control (BC) groups (p < 0.001). The anxiety and negative emotion scores were higher in the ID-RL group than in the ID-WL and ID-BC groups (p = 0.007 and p < 0.001, respectively). The KSS scores were lower in the RL group than in the WL and BC groups for both HS and ID group (both p < 0.001). The SOL was shorter in the HS-RL group than in HS-WL group (p = 0.019). Compared with the HS-BC group, the HS-RL group had an increase in microarousal index (MAI) and N1% (p = 0.034 and p = 0.021, respectively), while the total sleep time (TST) and sleep efficiency (SE) decreased (p = 0.001 and p < 0.001, respectively). Compared with the ID-WL group, the SOL was shorter in the ID-RL group (p = 0.043), while TST, SE, number of microarousals (NMA), and numbers of cycles of REM period were increased (p = 0.016, p = 0.046, p = 0.001, and p = 0.041, respectively). Compared with the ID-BC group, the ID-RL group had increases in the SOL, WASO, and the numbers of cycles and NMA in REM period (p = 0.038, p = 0.005, p = 0.045, and p = 0.033, respectively), and a decrease in SE (p = 0.014). The effects of ID-WL (vs. ID-RL group) and ID-BC (vs. ID-RL group) on SOL were mediated by negative emotions (mediating effects were - 37.626 and - 33.768, respectively). Red light can increase subjective alertness, anxiety, and negative emotions in both healthy subjects and people with ID, which can affect sleep directly or indirectly via the mediating effect of negative emotions.

0163 Impact of cold-water hand immersion on cognitive performance and sleepiness during sleep inertia

Abstract Introduction Sleep inertia is a state of impaired cognitive performance upon awakening that dissipates with time awake. Manipulation of the distal-to-proximal skin temperature gradient using cold water has been hypothesized as a potential countermeasure to sleep inertia, but not previously explored (Krauchi et al., 2004). This study examined the effects of cold-water hand immersion on subsequent cognitive performance and sleepiness during sleep inertia. Methods Ten healthy adults (mean±standard deviation [SD] age 23.2±4.96 years; 6M, 4F) have thus far completed an ongoing 8-day protocol. Prior to an overnight in-laboratory visit, participants maintained habitual 8h sleep schedules for 1 week at home. In-laboratory sleep opportunities were timed to coincide with habitual sleep time. Following at least 5-min of electroencephalogram (EEG) verified continuous slow wave sleep (SWS), participants were awakened twice during the night to submerge their non-dominant hand in warm (34 C) or ice-cold water (0 C) for 3 min in a randomized, crossover design. Sleep inertia was assessed with a Mathematical Addition Test (ADD) and the Karolinska Sleepiness Scale (KSS) at ~ 5, 15, and 25 min after each awakening. Outcomes included number of correct responses and median reaction time for correct responses on the ADD and KSS scores. Data were analyzed with mixed-model ANOVA with condition, condition order and time since awakening as fixed factors and subject as a random factor. Results The average (Mean±SD) amount of SWS prior awakening was similar before the cold 7.0±2.3 min and warm 6.6±1.0min conditions (p&amp;gt;0.10). Following cold water immersion, subjective sleepiness was reduced and the median reaction time for correct responses was faster compared with warm water immersion (main effects of condition, p’s&amp;lt; 0.05). The number of correct responses was not significantly different between conditions, nor were there any significant interaction effects among the fixed factors. Conclusion These preliminary findings indicate that cold-water hand immersion may reduce sleepiness and increase the speed of arithmetic calculations during sleep inertia, which could have important implications for military and first responders performing after awakenings from sleep. Support (if any) Office of Naval Research MURI N00014-15-1-2809; NIH RHL165343A and CTSA Grant UL1 TR002535; Undergraduate Research Opportunities Grant, University of Colorado Boulder.

0316 A Case Report: Comparing Sleep with and without blue light blockers

Abstract Introduction Blue light filtered eyewear is popular. Studies have looked at the effect of using blue light blockers in the evening but data is lacking on the effect of wearing blue light blockers (BLB) through the day. In this study we compared the effects of wearing BLB all day, on sleep and daytime sleepiness. Methods This is a single case report. A 32 year male wore an Actiwatch Pro and collected sleep diaries for 18 days. On days 1-9, non-blue light blocking eyewear (NBLB) were used all day. On days 10-18, BLB were used all day. Karolinska Sleepiness Scale (KSS) and Stanford Sleepiness Scale (SSS) during morning, afternoon and before sleep were recorded. IBM SPSS v. 29.0.0 is used for descriptive analysis, Pearson correlation and T-test comparison. Results White light exposure was not statistically different from BLB and NBLB. Data measured in minutes. Mean and standard deviation of in-bed duration with NBLB was 477.89±66.17 and with BLB was 518.06±53.06 (p=0.087). Sleep time with NBLB was 431.89±52.05 and with BLB was 471.72±48.49 (p=0.056). Wake After Sleep Onset (WASO) with NBLB was 43.78±18.63 and with BLB 46.33±14.25 (p=0.374). Percent Sleep with NBLB was 90.96±2.83% and with BLB was 91.09±2.29 (p=0.459). KSS scores for morning on NBLB was 1.75±1.035 and 1.00±0 with BLB (p= 0.023), afternoon NBLB 4.13±1.25, BLB 3.67±0.87 (p=0.194), before sleep NBLB 8.5±1.41 and 8.56±0.53 with BLB (p=0.457). SSS scores for morning on NBLB was 1.63±0.744 and 1.00±0 with BLB (p= 0.012), afternoon NBLB 3.38±1.06, BLB 3.56±0.88 (p=0.353), before sleep NBLB 7.00±1.41 and 7.89±0.60 with BLB (p=0.053). There was a strong correlation between white light exposure and increased WASO (Pearson 0.514) and strong negative correlation (Pearson -0.535) between white light exposure and percent of sleep duration. Conclusion Although there were no statistically significant differences between the sleep parameters between NBLB and BLB, we found a strong correlation between sleep time and white light exposure and negative correlation. When using BLB morning alertness was better. Support (if any)

Safety and pharmacodynamics of a single infusion of danavorexton in adults with obstructive sleep apnea experiencing excessive daytime sleepiness despite adequate use of CPAP

BackgroundSleep disruptions experienced by patients with obstructive sleep apnea (OSA) can lead to excessive daytime sleepiness (EDS) and significantly impact patients’ quality of life. EDS may persist despite use of continuous positive airway pressure (CPAP) therapy. Small molecules that target the orexin system, which has a known role in sleep-wake regulation, show therapeutic potential for the treatment of EDS in patients with hypersomnia. This randomized, placebo-controlled, phase 1b study aimed to investigate the safety of danavorexton, a small-molecule orexin-2 receptor agonist, and its effects on residual EDS in patients with OSA. MethodsAdults with OSA aged 18–67 years with adequate CPAP use were randomized to one of six treatment sequences of single IV infusions of danavorexton 44 mg, danavorexton 112 mg, and placebo. Adverse events were monitored throughout the study. Pharmacodynamic assessments included maintenance of wakefulness test (MWT), Karolinska Sleepiness Scale (KSS), and the psychomotor vigilance test (PVT). Results and conclusionAmong 25 randomized patients, 16 (64.0%) had treatment-emergent adverse events (TEAEs) and 12 (48.0%) had TEAEs considered related to treatment, all mild or moderate. Seven patients (28.0%) had urinary TEAEs: three, seven, and none while taking danavorexton 44 mg, danavorexton 112 mg, and placebo, respectively. There were no deaths or TEAEs leading to discontinuation. Improvements in mean MWT, KSS, and PVT scores were observed with danavorexton 44 mg and 112 mg vs placebo. These findings show that danavorexton can improve subjective and objective measures of EDS in patients with OSA and residual EDS despite adequate CPAP use.

Utilizing EEG and fNIRS for the detection of sleep-deprivation-induced fatigue and its inhibition using colored light stimulation

Drowsy driving is a common, but underestimated phenomenon in terms of associated risks as it often results in crashes causing fatalities and serious injuries. It is a challenging task to alert or reduce the driver’s drowsy state using non-invasive techniques. In this study, a drowsiness reduction strategy has been developed and analyzed using exposure to different light colors and recording the corresponding electrical and biological brain activities. 31 subjects were examined by dividing them into 2 classes, a control group, and a healthy group. Fourteen EEG and 42 fNIRS channels were used to gather neurological data from two brain regions (prefrontal and visual cortices). Experiments shining 3 different colored lights have been carried out on them at certain times when there is a high probability to get drowsy. The results of this study show that there is a significant increase in HbO of a sleep-deprived participant when he is exposed to blue light. Similarly, the beta band of EEG also showed an increased response. However, the study found that there is no considerable increase in HbO and beta band power in the case of red and green light exposures. In addition to that, values of other physiological signals acquired such as heart rate, eye blinking, and self-reported Karolinska Sleepiness Scale scores validated the findings predicted by the electrical and biological signals. The statistical significance of the signals achieved has been tested using repeated measures ANOVA and t-tests. Correlation scores were also calculated to find the association between the changes in the data signals with the corresponding changes in the alertness level.

Temporal dynamics of subjective sleepiness: A convergence analysis of two scales

ABSTRACT While sleepiness assessment metrics were initially developed in medical research, subjective sleepiness assessment is now widely used in both fundamental and applied studies. The Stanford Sleepiness Scale (SSS) and the Karolinska Sleepiness Scale (KSS) are often considered the gold standard in sleepiness research. However, their convergence and specific features have not been sufficiently investigated. The present study aims to analyse the dynamics and convergence of subjective sleepiness as measured by the KSS and SSS. A total of 208 adults participated in the experiment. Our findings suggest that sleepiness generally increased from the evening till night and was highest early in the morning. The SSS score appeared to be more sensitive to certain factors. The SSS and KSS scores strongly correlated with each other and converged on sleepiness assessment. However, the KSS showed a more even distribution of scores than the SSS. Currently, we are continuously expanding the SSDD.

Orexin 2 receptor-selective agonist danavorexton (TAK-925) promotes wakefulness in non-human primates and healthy individuals.

The orexin 2 receptor-selective agonist danavorexton (TAK-925) has been shown to produce wake-promoting effects in wild-type mice, narcolepsy-model mice, and individuals with narcolepsy type 1 and type 2. Here, we report wake-promoting effects of danavorexton in non-human primates and healthy men during their sleep phase. Electroencephalogram analyses revealed that subcutaneous administration of danavorexton significantly increased wakefulness in common marmosets (p < 0.05 at 0.1mg kg-1 , and p < 0.001 at 1mg kg-1 and 10mg kg-1 ) and cynomolgus monkeys (p ≤ 0.05 at 1mg kg-1 and 3mg kg-1 ). In a phase 1b crossover, randomized, double-blind, placebo-controlled and active-controlled study in sleep-deprived healthy participants (ClinicalTrials.gov identifier: NCT03522506), modafinil 300 mg (used to demonstrate assay sensitivity) and continuous infusion of danavorexton 44 mg and danavorexton 112 mg showed statistically superior wake-promoting effects to placebo (n=18). Measured using the Maintenance of Wakefulness Test, mean (standard deviation) sleep latencies during infusion of danavorexton 44 mg, danavorexton 112 mg and placebo were 21.4 (8.9), 31.8 (3.2) and 9.2 (6.4) min, respectively. Least-squares mean difference from placebo in average sleep latency was 16.8min with danavorexton 44 mg and 30.2min with danavorexton 112 mg (both p < 0.001). Karolinska Sleepiness Scale scores were statistically significantly lower (indicating decreased sleepiness) for participants receiving danavorexton than for those receiving placebo during infusion (danavorexton 44 mg, p=0.010; danavorexton 112 mg, p < 0.001). Together, these results indicate that an orexin 2 receptor agonist increases wakefulness in non-human primates and healthy individuals during their sleep phase.

Safety and pharmacodynamics of a single infusion of danavorexton in adults with idiopathic hypersomnia.

Idiopathic hypersomnia (IH) is a chronic disorder characterized by excessive daytime sleepiness unexplained by another disorder or drug/medication use. Although the orexin system plays a role in sleep-wake regulation, orexin A levels in the cerebrospinal fluid are normal in people with IH. This phase 1b, randomized, placebo-controlled, crossover study aimed to investigate the safety, pharmacokinetics, and pharmacodynamics of danavorexton, a small-molecule orexin-2 receptor agonist, in adults with IH. Adults with IH aged 18-75 years were randomized to one of two treatment sequences of single intravenous infusions of danavorexton 112 mg and placebo. Pharmacodynamic endpoints included the maintenance of wakefulness test (MWT), the Karolinska Sleepiness Scale (KSS), and the psychomotor vigilance task (PVT). Adverse events were monitored throughout the study period. Of 28 randomized participants, 12 (44.4%) had a treatment-emergent adverse event (TEAE) and 10 (37.0%) had a TEAE considered related to study drug, most of which were mild or moderate. Four participants (18.2%) had urinary TEAEs while receiving danavorexton, all of which were mild in severity. There were no deaths or TEAEs leading to discontinuation. Improvements in MWT, KSS, and PVT scores were observed with danavorexton compared to placebo. Following drug administration, a mean sleep latency of 40 min (maximum value) was observed during the MWT within 2 h of danavorexton infusion in most participants. A single infusion of danavorexton improves subjective and objective excessive daytime sleepiness in people with IH with no serious TEAEs, indicating orexin-2 receptor agonists are promising treatments for IH. Clinical Trial: Clinicaltrials.gov. https://clinicaltrials.gov/ct2/show/NCT04091438.

Correlation of the Karolinska sleepiness scale with performance variables of the monotonous bimanual psychomotor test

To assess the objectivity of measuring the level of sleepiness in the subjects using a monotonous psychomotor bimanual tapping test developed by us, performed on mobile devices running Android OS. Four hundred and ninety-four hour-long experiments with the performance of a psychomotor test were conducted on 102 students. Using the method of mixed linear models, correlations between the levels of sleepiness according to the Karolinska Sleepiness Scale (KSS) and the Epworth Sleepiness Scale (ESS) and the behavioral indicators of the test were evaluated. Statistically significant correlations between the increase in KSS scores and such indicators as a decrease in the total number of button taps and an increase in the frequency of «microsleep» episodes are shown. Statistically significant correlations of ESS score characteristics with the behavioral indicators of the test were not found. A large statistical material shows a reliable correlation of the parameters of the psychomotor test with the level of sleepiness on the Karolinska scale, which allows using the mobile application developed by us to determine the current level of sleepiness /alertness in the field.

Shift Work as a Risk Factor for Poor Sleep Quality and Daytime Sleepiness in Khorasan Railway Personnel in Iran

Background: Shift work disrupts the sleep rhythm and leads to daily sleepiness and physical and mental complications. Objectives: This study aimed to investigate the predictive role of shift work in poor sleep quality and daytime sleepiness in railway personnel. Methods: This descriptive-analytical and cross-sectional study was conducted on the employees of the Khorasan railway in Iran in 2021, 450 individuals of whom were selected as a sample using the census sampling method. The data collection method was through a checklist containing demographic information and related factors (e.g., employment history) and through a physician to evaluate underlying diseases, body mass index (BMI), smoking and use of substances (past medical history), and completion of standard questionnaires, including the Pittsburgh Sleep Quality Index (PSQI), Karolinska Sleepiness Scale (KSS), and STOP-BANG questionnaire. The data were analyzed using the t-test and simultaneous multivariate regression analysis by SPSS software (version 24). Results: Out of 450 employees, 144 (32%) and 306 (68%) subjects were day workers and shift workers, respectively. The average age of the participants was 40 ± 5.97 years. A significant difference was observed between the BMI with PSQI, KSS, and STOP-BANG scores (P = 0.001). Additionally, binary logistic regression analysis showed that shift work had a significant effect as a risk factor on both PSQI scores (CR = 1.25, 95% CI: 1.16-1.32, P = 0.001) and KSS scores (CR = 1.43, 95% CI: 1.29 - 1.59, P = 0.001). Conclusions: Shift work could increase the amount of sleepiness during work in personnel as the main cause, along with other effective factors, such as personal and occupational characteristics.

Flight crew fatigue risk assessment for international flights under the COVID-19 outbreak response exemption policy

BackgroundIn response to the COVID-19 outbreak, the Civil Aviation Administration of China (CAAC) has formulated Implementation Measures for Exemption of Crew Duty Periods and Flight Time Restrictions during the COVID-19 Outbreak. This exemption policy imposes temporary deviations from the approved crew duty periods and flight time restrictions for some transport airlines and regulates the use of multiple crews for continuous round-trip flights. However, no research has been conducted on flight crew fatigue under this exemption policy. That is, the exemption policy lacks theoretical analysis and scientific validation.MethodsFirstly, flight plans for international flights under both the exemption and the CCAR-121 Policy schemes (with three flight departure scenarios: early morning, midday and evening) are designed, and flight plans are simulated based on the SAFE model. The Karolinska Sleepiness Scale (KSS) and the PVT objective test of alertness, both of which are commonly used in the aviation industry, are then selected for use in an empirical experimental study of flight crew fatigue on two flights subject to the exemption and CCAR-121 policies.ResultsThe SAFE model simulation found that the fatigue risk results based on flight crews for flights departing in the early morning (4:00), at noon (12:00) and in the evening (20:00) indicate that the fatigue risk levels of flight crews operating under the exemption policy are overwhelmingly lower than or similar to those operating under the CCAR-121 policy. However, there were a few periods when the fatigue risk of crews flying under the exemption policy was higher than that of crews flying under the CCAR-121 policy, but at these times, the crews flying under both policies were either at a lower level of fatigue risk or were in the rest phase of their shifts. In the experimental study section, 40 pilots from each of the early morning (4:00), noon (12:00) and evening (20:00) departures operating under the exemption policy were selected to collect KSS scale data and PVT test data during their duty periods, and a total of 120 other pilots operating under the CCAR-121 policy were selected for the same experiment. First, the KSS scale data results found that flight pilots, whether flying under the exemption policy or under the CCAR-121 policy, had overall similar KSS scores, maintained KSS scores below the fatigue risk threshold (i.e., KSS score < 6) during the flights and that the empirical KSS data and the model simulation results from the KSS data were overall identical at the test nodes during the flight and had nearly identical trends. Finally, the results of the PVT objective test indicators showed that the overall change in 1/RT of the crews flying under the exemption policy was less than or similar to that of the crews flying under the CCAR-121 policy, while the maximum change in 1/RT of the crews under both policies was between 1 and 1.5. This indicates that the overall level of alertness of the crew flying under the exemption policy is higher than or similar to that of the crew flying under the CCAR-121 policy, while the change in alertness level of the crew before and after the mission is relatively small when flying under either policy.ConclusionBased on the model simulation results and the results of the empirical study, it was verified that the overall fatigue risk level of flight crews operating under the exemption policy is lower than or similar to the fatigue risk level of flight crews operating under the CCAR-121 policy. Therefore, the exemption policy in response to the COVID-19 outbreak does not result in an overall increase in the level of flight crew fatigue risk compared to the original CCAR-121 policy.

Effects of Low-Concentration Carbon Dioxide Exposure at Bedtime on Sleep in Adults With Insomnia Symptoms

Objectives: Carbon dioxide (CO2) accumulation in an enclosed space might cause drowsiness. This study aimed to assess the effect of bedtime exposure to low concentrations of CO2 gas on the sleep quality of adults with insomnia.Methods: In this double-blind, randomized, sham-controlled cross-over study, we consecutively recruited 24 adults (9 men; age, 55.4±6.3 y) complaining of sleep disturbances (Pittsburgh Sleep Quality Index ≥5). The following two interventions were used in the study: exposure to 2% low-concentration edible CO2 gas (experimental intervention) and exposure to room air (sham-controlled intervention). A sleep air device (Gosleep®, NYX), which atomizes CO2 gas, was used in both experimental and sham-controlled interventions. For the sham session, room air was generated for 18 min, and then, gradually reduced by degrees in the next 5 min with the device finally being turned off.Results: The group exposed to CO2 gas had longer time in bed (361.3±55.2 min vs. 347.2±35.7 min, p=0.034) and total sleep time (311.0±74.3 min vs. 287.2±69.4 min, p=0.010) than the group exposed to room air. Meanwhile, the total arousal (19.7±9.5/h vs. 24.0±13.7/h, p=0.011) and non-REM arousal (20.9±11.3/h vs. 25.1±14.9/h, p=0.008) indices were lower in the group exposed to CO2 gas than in the group exposed to room air. However, perceived total sleep time or sleep latency and Karolinska Sleepiness Scale scores were not significantly different between the two groups.Conclusion: Exposure to low concentrations of CO2 improved the total sleep time and arousal index in adults with insomnia. Unexpectedly, CO2 administration was found to be effective for sleep maintenance.

Effects of a palaeolithic diet on obstructive sleep apnoea occurring in females who are overweight after menopause—a randomised controlled trial

Background/ObjectivesObesity is the main risk factor for obstructive sleep apnoea, commonly occurring in females who are overweight after menopause. We aimed to study the effect of a palaeolithic diet on sleep apnoea in females with overweight after menopause from the population.MethodsSeventy healthy, non-smoking females with a mean age of 60 years and a mean BMI of 33 kg/m2 were randomised to a palaeolithic diet or to a control low-fat diet according to Nordic Nutritional Recommendations, for 2 years. The apnoea-hypopnoea index was measured and daytime sleepiness was estimated during the intervention.ResultsThe mean apnoea-hypopnoea index at baseline was 11.6 (95% CI 8.6–14.5). The mean weight loss was 7.2 kg (95% CI 5.3–9.2 kg) in the palaeolithic diet group and 3.9 kg in the control group (95% CI 1.9–5.9 kg); p < 0.021 for the group difference. The reduction in weight corresponded to a reduction in the apnoea-hypopnoea index in the palaeolithic diet group (r = 0.38, p = 0.034) but not in the control group (r = 0.08, p = 0.69). The apnoea-hypopnoea index was reduced in the palaeolithic diet group when the weight was reduced by more than 8 kg. Daytime sleepiness according to the Epworth Sleepiness Scale score and the Karolinska Sleepiness Scale score was unaffected by dietary group allocation.ConclusionsA substantial decrease in body weight of 8 kg was needed to achieve a reduction in sleep apnoea in this small trial of women who are overweight after menopause. The palaeolithic diet was more effective for weight reduction than a control low-fat diet and the reduction in sleep apnoea was related to the degree of weight decrement within this diet group.Trial registrationClinicaltrials.gov: NCT00692536.

Association Between High Risk of Obstructive Sleep Apnea and Excessive Daytime Sleepiness in Elderly People Based on Epworth Sleepiness Scale and Karolinska Sleepiness Scale after Exposure to Low Frequency Whole Body Vibration

Background: The most common symptom of obstructive sleep apnea (OSA) is excessive daytime sleepiness (EDS). Aim: To look for the high risk of OSA in the elderly population and its association with increased Epworth sleepiness scale (ESS) and Karolinska sleepiness scale (KSS) scores after exposure with low-frequency whole body vibration (LFWBV). Method: This study used a one group pretest-post test design. Subjects examined for Snoring Score (SS), ESS and KSS scores, after which subjects were given exposure to LFWBV and examined for post-exposure KSS scores. Results: There were more elderly people who have a high risk of OSA. The ESS score showed a non-significant relationship between high risk of OSA and the incidence of EDS based on an increase in ESS score (r 0.401; p value 0.064) and the degree of sleepiness based on the KSS score after LFWBV exposure (r 0.296; p value 0.181), although ESS scores were higher in the group with high risk of OSA (mean score 4.85; p value 0.003). Discussion: The results of this study are consistent with several other studies which show no significant correlation between high risk of OSA and increased ESS scores. LFWBV does provide comfort and increases the degree of sleepiness in subjects with or without a high risk of OSA. Conclusion: Older age increases the risk of OSA, but does not cause EDS. LFWBV caused an increase in the degree of sleepiness, both the high-risk and non-high-risk OSA groups. Keywords: Obstructive sleep apnea, Epworth sleepiness scale, whole body vibration, Karolinska sleepiness scale.