Epidemiology of sleep patterns and circadian typology in uruguayan children: The contribution of school shifts.

Healthy sleep is defined by the combination of adequate duration, good quality, and regular timing. In children, sleep thus depends on the interplay of individual, parental, organizational, community, and social variables, but only a few studies have addressed this issue in a comprehensive way nationwide. Using the Uruguayan nationally representative survey (Nutrition, Child Development, and Health Survey, Encuesta de Nutrición, Desarrollo Infantil y Salud, ENDIS), we present the first epidemiological characterization of chronobiological and sleep parameters in Latin American children. On average, Uruguayan urban children (n = 2437; 5-10-years old) showed quite late chronotypes (MSFsc = 03:53 ± 1:07), moderate misalignment (SJL = 1.0 ± 0.9 h), and adequate sleep duration (SDweek = 9.9 ± 1.0 h). Further, we show the substantial influence of school shift schedules on children's circadian typology and sleep patterns. Our results show that children attending the morning school shift have a higher risk of sleep problems than afternoon-school shift ones. The chronotype and sleep were earlier in morning-school shift children than in children attending the afternoon school shift. However, morning-school shift children had stronger misalignment, shorter sleep on school days, and a higher risk of chronic sleep deficit and non-healthy circadian misalignment (even worse in late chronotypes) than afternoon-shift children. This evidence points to the need of evaluating policies to reorganize school start times to prevent the negative effects that early schooling seems to have on children's sleep health, which has been neglected so far.

Daily-level associations between sleep duration and next-day alcohol and cannabis craving and use in young adults.

STUDY OBJECTIVES: To examine the effects of sleep duration on next-day alcohol and cannabis craving and use among young adults. METHOD: A community sample of young adults who reported recent simultaneous alcohol and cannabis use at screening (N = 409; Mage = 21.61; 50.9% female) completed twice daily surveys (morning and afternoon) for five 14-day sampling bursts (i.e., 70 days total). Daily measurements included sleep duration, alcohol and cannabis craving, and alcohol and cannabis use (i.e., number of drinks, hours high). Multilevel models enabled examining associations between sleep duration and substance use/craving at three distinct levels: daily-level, burst-level, and person-level. RESULTS: At the day-level, sleep duration was inversely associated with craving for both alcohol and cannabis: Stronger craving was reported on mornings and afternoons after relatively shorter sleep duration. At the burst-level, sleep duration was inversely associated with morning and afternoon alcohol craving indicating stronger alcohol craving, but not cannabis craving, during two-week periods when young adults have accumulated shorter sleep duration. Pertaining to alcohol and cannabis use, no daily-level effects were found, but the burst-level effect showed that participants engaged in greater alcohol use during two-week bursts with shorter sleep duration. CONCLUSIONS: Based on a non-clinical sample of young adults reporting substance use, results suggest shorter sleep duration may be a modifiable risk factor as it pertains to substance use and cravings. Results highlight day-level effects of shorter sleep duration on substance use cravings and adverse effects of cumulative sleep deficit on alcohol use.

How Much Sleep Does an Elite Athlete Need?

PURPOSE: Anecdotal reports indicate that many elite athletes are dissatisfied with their sleep, but little is known about their actual sleep requirements. Therefore, the aim of this study was to compare the self-assessed sleep need of elite athletes with an objective measure of their habitual sleep duration. METHODS: Participants were 175 elite athletes (n = 30 females), age 22.2 (3.8) years (mean [SD]) from 12 individual and team sports. The athletes answered the question "how many hours of sleep do you need to feel rested?" and they kept a self-report sleep diary and wore a wrist activity monitor for ∼12 nights during a normal phase of training. For each athlete, a sleep deficit index was calculated by subtracting their average sleep duration from their self-assessed sleep need. RESULTS: The athletes needed 8.3 (0.9) hours of sleep to feel rested, their average sleep duration was 6.7 (0.8) hours, and they had a sleep deficit index of 96.0 (60.6) minutes. Only 3% of athletes obtained enough sleep to satisfy their self-assessed sleep need, and 71% of athletes fell short by an hour or more. Specifically, habitual sleep duration was shorter in athletes from individual sports than in athletes from team sports (F1,173 = 13.1, P < .001; d = 0.6, medium), despite their similar sleep need (F1,173 = 1.40, P = .24; d = 0.2, small). CONCLUSIONS: The majority of elite athletes obtain substantially less than their self-assessed sleep need. This is a critical finding, given that insufficient sleep may compromise an athlete's capacity to train effectively and/or compete optimally.

Effects of the COVID-19 lockdown on sleep duration in children and adolescents: A survey across different continents.

BACKGROUND: A parent survey was conducted to assess the sleep habits of children residing in various countries before and during the SARS-CoV-2 pandemic. It was hypothesized that lockdown would be associated with increased sleep duration. METHODS: Outcomes were changes in bedtime, wake time, and sleep duration in the pandemic compared to before. Logistic regression was applied to evaluate the effects of age and covariates on outcomes. RESULTS: A total of 845 questionnaires completed from May 1 to June 10, 2020 were analyzed (45.8% female; age 3-17 years). During the pandemic, 23.1% of preschoolers, 46.2% of school-age children, and 89.8% of adolescents were going to bed after 10 p.m. on weekdays compared to 7.1%, 9.4%, and 57.1% respectively before the pandemic, with these proportions being higher on weekends. Likewise, 42.5% of preschoolers, 61.3% of school-age children, and 81.2% of adolescents were waking after 8 a.m. on weekdays (11.6%, 4.9%, and 10.3%, before) with these proportions being greater on weekends. Sleep duration did not change in 43% of participants on weekdays and in 46.2% on weekends. The 14-17 years group had fourfold increased odds for longer sleep duration on weekdays (p < .01), and children aged 6-13 years had twofold increased odds for longer sleep duration on weekends relative to the 3-5 years age group (p = .01). CONCLUSIONS: Although lockdown was associated with later bedtime and wake time, this shift did not alter sleep duration in more than 40% of children. Yet, compared to preschoolers, high school-aged children were more likely to sleep more on weekdays and primary school children on weekends.

Weekend catch-up sleep is associated with reduced metabolic derangements in Korean adults.

BACKGROUND: Deficits in sleep are associated with metabolic derangements, but the effect of sleep supplementation on metabolic derangements remains to be elucidated. This study aimed to investigate whether weekend catch-up sleep is associated with metabolic derangements in Korean adults. METHODS: A total of 10,749 individuals over 40 years old were identified from the 2016-2017 Korea National Health and Nutrition Examination Survey. Data on demographics, health behaviors, self-reported sleep duration, and physician-diagnosed metabolic diseases were used in this analysis. The odds ratio for each metabolic derangement was determined via stepwise multivariable logistic regression models. RESULTS: Short weekday sleep and insufficient weekend catch-up sleep were independently associated with an increased risk for all metabolic derangements, except hypertension. Individuals who did not make up sleep on the weekend were more likely to be obese and have type 2 diabetes or hypercholesterolemia.

Short Sleep Duration and Extremely Delayed Chronotypes in Uruguayan Youth: The Role of School Start Times and Social Constraints.

During adolescence, biological, psychosocial, and contextual factors converge in a "perfect storm" and have been put forward to explain the delay in chronotype observed at this age and the prevalence of disrupted sleep. This study provides evidence to support that chronotype and sleep patterns (particularly sleep duration) are socially constrained and to identify novel significant social predictors. Uruguayan public school activities are arranged in up to 4 shifts, creating a natural experiment to examine the effect of school timing on questionnaire-based assessments of sleep and chronotype. In this study, 268 high school students (15-18 years old) who attended school either on morning (0730 to 1130 h) or afternoon shifts (1130 h to 1530 h) responded to an adapted School Sleep Habits Survey. Students attending afternoon shifts had later chronotypes (a 1.5-h later midpoint of sleep on free days adjusted for sleep debt) than those attending the morning shift. Besides shift, evening social activities (including dinner time) were further identified as key predictors of late chronotypes, whereas age and gender were not. Sleep on school days was overall advanced and reduced with respect to weekends, and these effects were stronger in morning-shift students. Weekend sleep duration was similar between shifts, which probably caused the prevalence of reduced sleep durations (average weekly sleep duration, SDweek <8 h) to be higher in morning-shift students (almost 80%) than in afternoon-shift ones (34%). Reduced sleep duration was significantly higher in morning-shift students. In addition, age, chronotype, and dinner time became relevant determinants of sleep deficit only in the morning-shift students. Besides the important social constraint of early school start time, this is the first study to confirm the significance of other types of social pressures on both adolescents' chronotype and sleep deficit, which can be useful as potential new targets for effective policies to protect adolescent sleep.

Sleep versus non-sleep-related fatal road accidents.

OBJECTIVE: To study different factors that are associated with fatal sleepiness-related motor vehicle accidents (FSMVA) and in other types of fatal motor vehicle accidents (FMVA) in Finland. METHODS: All FMVA that were caused by falling asleep at the wheel (FSMVA) during the years 2005-2014 were investigated using OTI (Finnish Crash Data Institute) data. The control group consisted of 136 drivers who died in other types of FMVA in 2013. A total of 258 accidents were investigated. RESULTS: The mean age of the 122 drivers in the FSMVA group was 44 (standard deviation 19) years; there were 100 men (82%) and 22 women. The mean age of the 136 control drivers was 45 (standard deviation 19) years; there were 116 men (85%) and 20 women. Short sleep time (<6 h) during the previous night before the accident was the most prominent independent risk factor for FSMVA compared to other FMVA (p < 0.05). None of the other driver-related factors (diseases, blood alcohol level, illegal drugs, body mass index, medications, age, sex) differed significantly between the two groups. CONCLUSION: Short sleep is a major cause of fatal sleepiness-related motor vehicle accidents. Driver health factors such as sleep apnea or acute/chronic diseases as well as use of sedative medications and drugs are known risk factors for FSMVA, but these factors are associated also with other types of accidents. Healthy individuals are at risk for falling asleep while driving if they are sleep deprived. All drivers should be aware of the importance of adequate sleep.

The characteristics and clinical significance of REM<10% in children with sleep-disordered breathing.

OBJECTIVE: Fractional time in REM sleep <20% ('little REM sleep') is indicative of more severe sleep-disordered breathing (SDB) in adults. We examined if other REM% is predictive of more severe SDB in children. METHODS: In this retrospective study of 616 pediatric SDB patients, age, sex ratio, BMI, sleep efficiency, awakening frequency, sleep latency, apnea-hypopnea index (AHI), obstructive apnea index (OAI), and lowest oxygen pulse saturation (LSpO2) were compared among groups stratified according to REM%: REM≥20%, REM<20%, 15% ≤ REM<20%, 10% ≤ REM<15%, and REM<10%. Correlations with AHI, OAI, LSpO2, sleep efficiency, and awakening frequency were examined in REM<20% and REM<10% groups. Associations of these parameters with REM<10% were examined by single- and multifactor regression. RESULTS: Pediatric SDB patients with little REM sleep demonstrated poorer sleep quality than patients with REM≥20%, while patients with REM<10% also exhibited more severe SDB. Specifically, the REM<20% group exhibited higher number of awakenings and lower sleep efficiency than the REM≥20% group (both P ≤ 0.001), as did each REM%<20% subgroup (lower sleep efficiency: all P < 0.05; higher awakening frequency: all P < 0.001). Moreover, compared to the REM≥20% group, the REM<10% also exhibited higher AHI (P = 0.025) and lower LSpO2 (P = 0.019). In the REM<10% group, individual REM% was negatively correlated with AHI (r = -0.216, P = 0.031) and positively with LSpO2 (r = 0.2, P = 0.046). Multifactor logistic regression correcting for age and BMI identified AHI as an independent predictor of REM<10% (P = 0.012, OR = 1.016, 95% CI [1.004,1.029]). CONCLUSION: REM% <10% is associated with poor sleep quality and SDB severity in children, suggesting that this threshold should define "little REM sleep" in pediatric patients.

Changes in sleep habits between 1985 and 2013 among children and adolescents in Sweden.

AIMS: The aim was to investigate changes in child and adolescent sleep habits in Sweden over time. This had not been done previously. METHODS: Cross-sectional questionnaire data over three decades of investigations of the Health Behaviours of School Children study (1985/1986, 2005/2006 and 2013/2014) were used. The sample included 18,682 children and adolescents, aged 11, 13 and 15. Empirically based age-specific sleep duration recommendations were used to operationalise sleep duration. RESULTS: The results showed that, over time, fewer go to bed early and more go to bed late. Regarding sleep duration, there have been decreases in the proportion of children and adolescents that sleep as much as is recommended for their age. Sleep onset difficulties have increased for all ages and increase the odds of sleeping less than recommended as well as having late bedtimes. Boys were more likely than girls to have later bedtimes and to sleep less than recommended. A vocational educational track, not planning to study further or being unsure of which track to choose increased the odds for 15 year olds to have late bedtimes and to sleep less than recommended compared with a college preparatory track. CONCLUSIONS: The results indicate that over time, fewer children and adolescents attain sufficient sleep duration. This may have implications for study results, mental health and cognitive abilities.

Deterioro psicomotor por déficit de sueño en estudiantes de Medicina / Sleep deficit in medical students and psychomotor skills deteriorations

Introducción: Durante los últimos años se ha enfatizado la importancia que los trabajadores de la salud deban tener una cantidad mínima de horas de sueño. Se ha encontrado que los daños por la falta de sueño se ven implicados en el deterioro físico y mental, además se ha asociado al error médico. Objetivos: El objetivo de este estudio es evaluar si existe un deterioro psicomotor en estudiantes de medicina y así establecer si es necesario modificar las prácticas médicas para mejorar la función cognitiva de estudiantes y así optimizar la atención a pacientes. Métodos: En este estudio se utilizó el programa de entrenamiento cognitivo, Lumosity. (5) Con esta herramienta fue posible realizar mediciones de destrezas psicomotoras en estudiantes de medicina en un estado de desvelo y en un estado en el que habían dormido más de seis horas. Además, se compararon los resultados y se determinó si existía o no una diferencia significativa en ambas poblaciones. Estudio abierto transversal de 52 estudiantes de sexto y séptimo año de la Facultad de Medicina de la Universidad Francisco Marroquín. Resultados: Se encontró evidencia estadísticamente significativa que indica que hay deterioro psicomotor por falta de sueño en estudiantes de sexto y séptimo año de medicina. Se obtuvieron mayores puntuaciones en Lumosity en los grupos pre guardia que en los grupos post guardia (puntaje promedio de grupo pre guardia: 2912 vs. puntaje promedio de grupo post guardia: 2515). Conclusiones: Existe un deterioro psicomotor por falta de sueño en estudiantes de sexto y séptimo año de medicina. Palabras clave: Deterioro psicomotor, Lumosity, guardia y pre guardia

Background. Recent papers have emphasized the importance of sufficient sleep in health practitioners to avoid skill deterioration. Lack of sleep often leads to physical and mental deterioration and medical error. Objective. The purpose of this study is to evaluate if there is a psychomotor deterioration in medical students and to determine if modifying medical practices is necessary to improve cognitive function in medical students, thus assuring a better quality service to patients. Methods. Lumosity test (5) cognitive training program was used, which allowed data recollection of psychomotor skills from medical students who were sleep deprived and from students who had slept at least six hours; then, the data was compared. Open transversal study with 52 medical students in the last two years of their career from Universidad Francisco Marroquín. Results: There was statistically significant evidence indicating that there is a psychomotor deterioration due to sleep deprivation in medicine students during their last year. Lumosity mean scores in the group that had slept six hours and in the sleep-deprived group were 2912 and 2515, respectively. Conclusions: There is a psychomotor deterioration due to a lack of sleep in medical students working long hospital calls. Key words: Sleep deficit; psychomotor skills; Lumosity test

Neuroligin 3 R451C mutation alters electroencephalography spectral activity in an animal model of autism spectrum disorders.

Human studies demonstrate that sleep impairment is a concurrent comorbidity of autism spectrum disorders (ASD), but its etiology remains largely uncertain. One of the prominent theories of ASD suggests that an imbalance in synaptic excitation/inhibition may contribute to various aspects of ASD, including sleep impairments. Following the identification of Nlgn3R451C mutation in patients with ASD, its effects on synaptic transmission and social behaviours have been examined extensively in the mouse model. However, the contributory role of this mutation to sleep impairments in ASD remains unknown. In this study, we showed that Nlgn3R451C knock-in mice, an established genetic model for ASD, exhibited normal duration and distribution of sleep/wake states but significantly altered electroencephalography (EEG) power spectral profiles for wake and sleep.

How to promote patients' sleep in hospital.

Rationale and key points Disturbed or disrupted sleep is associated with adverse effects on physical and psychological health. This article explores the importance of promoting patients' sleep in hospital, although some of the principles can be applied to other healthcare settings. Sleep is essential to recovery and well-being, and nurses are well placed to support patients to achieve and sustain sleep. ¼ Sleep has a restorative function and is particularly important in maintaining patients' health and well-being. ¼ Sleep deficit has been linked to obesity, type 2 diabetes, cardiovascular disease and some cancers. ¼ Assessment of patients' sleep routines and patterns, and consideration of environmental factors enables nurses to identify that which assists and limits sleep, and take appropriate action. Reflective activity 'How to' articles can help you update your practice and ensure it remains evidence-based. Apply this article to your practice. Reflect on and write a short account of: ¼ How you think this article will change your practice when promoting sleep in patients in your care. ¼ How you could use this article to educate your colleagues.

The influence of school time on sleep patterns of children and adolescents.

OBJECTIVE: This epidemiological study evaluated the impact of school time on sleep parameters of children and adolescents. METHODS: This cross-sectional study involved 639 elementary and high school students (mean age 13.03 years, range 8-18, 58.5% female) from the south of Brazil. Participants answered the Morningness-Eveningness Questionnaire (MEQ), and were asked about their sleeping habits on weekdays and weekends. Sleep deficit was defined as the difference between sleep duration on weekdays and weekends. RESULTS: The morning-school-time students presented significantly higher age, bedtime and wake up differences, sleep deficits, and social jetlag. The sleep deficit presented by girls was greater than that observed in boys of the same age. The difference between weekday and weekend waking times was also significantly greater in girls than in boys aged 13-18 years. Sleep deficit was significantly positively correlated with age and differences in wake up times, and significantly negatively correlated with MEQ scores, social jetlag, difference between weekday and weekend bedtimes, midpoint of sleep on weekends, and midpoint of sleep on weekends corrected for sleep deficit. A step-by-step multivariate logistic regression identified social jetlag, the difference between waking times on weekdays and weekends, and the midpoint of sleep on weekends as significant predictors of sleep deficit (Adjusted R(2) = 0.95; F = 1606.87; p <0.001). CONCLUSION: The results showed that school time influences the sleep parameters. The association of school schedules and physiological factors influence the sleep/wake cycle.

Promoting healthy sleep.

Nurses are accustomed to helping others with their sleep problems and dealing with issues such as pain that may delay or interrupt sleep. However, they may be less familiar with what constitutes a healthy night's sleep. This article examines what is known about the process and purpose of sleep, and examines the ways in which factors that promote wakefulness and sleep combine to help establish a normal circadian rhythm. Theories relating to the function of sleep are discussed and research is considered that suggests that sleep deficit may lead to metabolic risks, including heart disease, obesity, type 2 diabetes mellitus and several types of cancer.

Sleep duration and patterns in adolescents: correlates and the role of daily stressors.

OBJECTIVES: The first aim of this study was to assess the prevalence of sleep deficit in a large sample of adolescents. Second, the study aimed to assess whether short sleep duration in the sample was associated with emotional and behavioral problems. Lastly, the study aimed to investigate the association between daily stressors--bedtime activities and sleep duration. DESIGN: Cross-sectional survey. SETTING: The questionnaires were completed during school hours in 17 municipal junior high schools in Sweden. PARTICIPANTS: A total of 2767 adolescents aged 12 to 16 years, 48% girls. MEASUREMENTS AND RESULTS: Sleep measures included total sleep time (TST) for schooldays and weekends, obtained as combined measures of self-reported bed-time, wake-time, and sleep onset latency. We used the new National Sleep Foundation's guidelines to operationalize sleep duration. Overall 12% of younger adolescents (age 12-13 years) and 18% of older adolescents (14-16 years) slept less than recommended (TST < 7 hours). Adolescents reporting nonrecommended TST also reported more behavioral (ie, norm-breaking behaviors) and emotional problems (ie, depression, anxiety, and anger), with effects in the small-medium range. Finally, adolescents reporting bedtime arousal and use of information and communication technology in bed were more likely to report TST < 7 hours. Stress at home (for younger adolescents) and stress of school performance (for older adolescents) were also associated with TST less than 7 hours. CONCLUSIONS: The new National Sleep Foundation's recommendations were informative in this context. Future sleep interventions need to target barriers to good sleep practices, such as use of information and communication technology, stress, and worry that may contribute to arousal at bedtime.

Behavioral sleep-wake homeostasis and EEG delta power are decoupled by chronic sleep restriction in the rat.

STUDY OBJECTIVES: Chronic sleep restriction (CSR) is prevalent in society and is linked to adverse consequences that might be ameliorated by acclimation of homeostatic drive. This study was designed to test the hypothesis that the sleep-wake homeostat will acclimatize to CSR. DESIGN: A four-parameter model of proportional control was used to quantify sleep homeostasis with and without recourse to a sleep intensity function. SETTING: Animal laboratory, rodent walking-wheel apparatus. SUBJECTS: Male Sprague-Dawley rats. INTERVENTIONS: Acute total sleep deprivation (TSD, 1 day × 18 or 24 h, N = 12), CSR (10 days × 18 h TSD, N = 5, or 5 days × 20 h TSD, N = 6). MEASUREMENTS AND RESULTS: Behavioral rebounds were consistent with model predictions for proportional control of cumulative times in wake, nonrapid eye movement (NREM) and rapid eye movement (REM). Delta (D) energy homeostasis was secondary to behavioral homeostasis; a biphasic NREM D power rebound contributed to the dynamics (rapid response) but not to the magnitude of the rebound in D energy. REM behavioral homeostasis was little affected by CSR. NREM behavioral homeostasis was attenuated in proportion to cumulative NREM deficit, whereas the biphasic NREM D power rebound was only slightly suppressed, indicating decoupled regulatory mechanisms following CSR. CONCLUSIONS: We conclude that sleep homeostasis is achieved through behavioral regulation, that the NREM behavioral homeostat is susceptible to attenuation during CSR and that the concept of sleep intensity is not essential in a model of sleep-wake regulation. STUDY OBJECTIVES: Chronic sleep restriction (CSR) is prevalent in society and is linked to adverse consequences that might be ameliorated by acclimation of homeostatic drive. This study was designed to test the hypothesis that the sleep-wake homeostat will acclimatize to CSR. DESIGN: A four-parameter model of proportional control was used to quantify sleep homeostasis with and without recourse to a sleep intensity function. SETTING: Animal laboratory, rodent walking-wheel apparatus. SUBJECTS: Male Sprague-Dawley rats. INTERVENTIONS: Acute total sleep deprivation (TSD, 1 day × 18 or 24 h, N = 12), CSR (10 days × 18 h TSD, N = 5, or 5 days × 20 h TSD, N = 6). MEASUREMENTS AND RESULTS: Behavioral rebounds were consistent with model predictions for proportional control of cumulative times in wake, nonrapid eye movement (NREM) and rapid eye movement (REM). Delta (D) energy homeostasis was secondary to behavioral homeostasis; a biphasic NREM D power rebound contributed to the dynamics (rapid response) but not to the magnitude of the rebound in D energy. REM behavioral homeostasis was little affected by CSR. NREM behavioral homeostasis was attenuated in proportion to cumulative NREM deficit, whereas the biphasic NREM D power rebound was only slightly suppressed, indicating decoupled regulatory mechanisms following CSR. CONCLUSIONS: We conclude that sleep homeostasis is achieved through behavioral regulation, that the NREM behavioral homeostat is susceptible to attenuation during CSR and that the concept of sleep intensity is not essential in a model of sleep-wake regulation.

Measuring individual vulnerability to sleep loss--the CHICa scale.

The aim of this project was to construct a psychometrically satisfying scale to describe subjective reactions to sleep deprivation. First, on the basis of a literature review, a list of items was generated which reflected the negatively affected mood and reduced wellbeing associated with sleep loss. Additionally, psychology students were asked to describe their cognitive and emotional symptoms following a night with curtailed sleep. As a result, 69 items were included in the experimental set. University students (n = 102, females, mean age 22.5 ± 1.9 years) completed the form several times during 1 week in June (while preparing for examinations) and on a free day in September; a total of 460 forms were collected. The final, 26-item version of the scale was validated in a sleep deficit experiment lasting 1 week, conducted with 25 female participants (mean age 23.4 ± 1.9 years). Factor analysis showed 71.7% of total variance explained by four components: impaired thermoregulation (C for cold), disrupted appetite (H for hunger), affective problems (I for irritability) and lowered level of cognitive functioning (Ca for cognitive attenuation). A Polish version of the CHICa scale showed satisfactory psychometric properties. Cronbach's alpha of the subscales were between 0.90 and 0.95. All four subscales exhibited a significant increase with an experimental 3-h daily sleep restriction over a period of 1 week; cognitive attenuation was the most symptomatic. Cognitive problems (reduced concentration, comprehension and accuracy) and a lack of energy seem to be the most specific subjective manifestations of the chronic sleep deficit state. CHICa may be helpful in research on inter-and intra-individual differences and on the efficacy of various counteractive treatments for the consequences of sleep deprivation.