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Summary: For a good night's sleep, we consensually recommend avoiding alcohol, smoking and drugs. However, these addictions are highly prevalent in the general population, and it is difficult to estimate their real impact on sleep. The aim of this study is to clarify the association between sleep habits and disorders, and addictions. The design was a telephone crossover national recurrent health poll survey (Santé publique France, Baromètre santé, 2017; Questionnaire, pp. 53; Saint Maurice) in a representative sample of French adults. There were 12,367 subjects (18–75 years old) who answered the survey. Sleep log items assessed sleep schedules (total sleep time) on work and leisure days: at night, while napping, and over 24 hr using a sleep log. Retained items include: (1) short sleep (≤ 6 hr/24 hr); (2) chronic insomnia (International Classification of Sleep Disorders, 3rd edition criteria); and (3) chronotype (evening–morning–neutral). Psychoactive substances retained included tobacco (current or former users), alcohol (daily consumption and weekly binge drinking), cannabis (Cannabis Abuse Screening Test), and other drugs (consumption during the past year). We found that: (1) daily smokers (lightly or heavily dependent) were more frequently short sleepers than occasional smokers and non‐smokers; (2) heavily dependent daily smokers were more likely to suffer from insomnia than other smokers or non‐smokers; (3) short sleep and insomnia were not significantly associated with the consumption of alcohol, cannabis or any other drug; (4) the evening chronotype was significantly associated with the consumption of tobacco, alcohol and cannabis. In conclusion, our study highlights significant relationships between the use of psychoactive substances and sleep characteristics among adults, emphasizing the need to take into account each subject individually. [ABSTRACT FROM AUTHOR]

Background: The outbreak of the Covid-19 pandemic and the accompanying lockdown measures have had a major impact on societies around the world, leading to sleep problems for a large part of the population. In order to assess the sustainability of sleeping troubles related to the sanitary crisis, it was crucial to measure its prevalence after the end of the Covid-19 confinement.Methods: As part of an epidemiological survey on Covid and Confinement (COCONEL), we enquired on sleep disorders using two items in 4 repetitive cross-sectional surveys. The first took place during the first week of the French confinement (March 31 to April 2; N = 1005 participants). The second took place in the middle of this period (April 15-17; N = 1005). The two last surveys were held at the end of the confinement (May 7-10; N = 2003) and one month after the end (June 10-12; N = 1736). Using a random constant, the mixed model took into account the longitudinal character of the last two waves (intra-individual correlations for individuals surveyed in waves 3 and 4).Results: The prevalence of sleep problems significantly decreased during the last weeks of the confinement, and this trend was confirmed one month after the end of confinement. One quarter of the population reported that their sleep was better one month after the end of the confinement. Sleep improvement was reported more often by women and people aged less than 65. Such improvement was less frequent among those who were still highly exposed to the pandemic's media coverage after the end of the confinement.Conclusion: The possibility of recovering a good sleep largely depends on the type of sleep disorder. The decrease in sleep problems occurred mainly among people with mild sleep problems during the confinement. Further research is needed to assess the long-term effects of the Covid-19 pandemic and its confinement period on sleep quality in the general population. [ABSTRACT FROM AUTHOR]

Introduction: Short total sleep time (TST < 6 h) is a strong major health determinant that correlates with numerous metabolic, cardiovascular and mental comorbidities, as well as accidents. Our aim was to better understand, at a population level, how adults adapt their TST during the week, and how short sleepers and those with sleep debt and sleep restriction use napping or catching up on sleep during weekends (ie, sleep debt compensation by sleeping longer), which may prevent these comorbidities.Methods: A large representative sample of 12,367 subjects (18-75 years old) responded by phone to questions about sleep on a national recurrent health poll (Health Barometer, Santé Publique France 2017) assessing sleep schedules (TST) at night, when napping, and over the course of a 24-h period while using a sleep log on workdays and weekends. Retained items were: (1) short sleep (TST ≤ 6 h/24 h); (2) chronic insomnia (international classification of sleep disorders third edition, ICSD-3 criteria); (3) sleep debt (self-reported ideal TST - TST > 60 min, severe > 90 min); and (4) sleep restriction (weekend TST - workday TST = 1-2 h, severe > 2 h).Results: Average TST/24 h was 6h42 (± 3 min) on weekdays and 7h26 (± 3 min) during weekends. In addition, 35.9% (± 1.0%) of the subjects were short sleepers, 27.7% (± 1.0%) had sleep debt (18.8% (± 0.9%) severe), and 17.4% (± 0.9%) showed sleep restriction (14.4% (± 0.8%) severe). Moreover, 27.4% (± 0.9%) napped at least once per week on weekdays (average: 8.3 min (± 0.5 min)) and 32.2% (± 1.0%) on weekend days (13.7 min (± 0.7 min)). Of the 24.2% (± 0.9%) of subjects with severe sleep debt (> 90 min), only 18.2% (± 1.6%) balanced their sleep debt by catching up on sleep on weekends (14.9% (± 0.8%) of men and 21.5% (± 0.9%) of women), and 7.4% (± 1.2%) of these subjects balanced their sleep debt by napping (7.8% (± 0.5%) of men and 6.6% (± 0.4%) of women). The remaining 75.8% (± 5.4%) did not do anything to balance their severe sleep debt during the week.Discussion and Conclusions: Short sleep, sleep debt, and sleep restriction during weekdays affected about one third of adults in our study group. Napping and weekend catch-up sleep only compensated for severe sleep debt in one in four subjects. [ABSTRACT FROM AUTHOR]

Professional burnout syndrome has been described in association with insomnia and metabolic, inflammatory and immune correlates. We investigated the interest of exploring biological parameters and sleep disturbances in relation to burnout symptoms among white-collar workers. Fifty-four participants with burnout were compared to 86 healthy control participants in terms of professional rank level, sleep, job strain (Karasek questionnaire), social support, anxiety and depression (HAD scale). Fasting concentrations of glycaemia, glycosylated hemoglobin (HbA1C), total-cholesterol, triglycerides, C-reactive protein (CRP), thyroid stimulating hormone (TSH), 25-hydroxyvitamin D (25[OH]D), and white blood cell (WBC) counts were assessed. Analysis of variance and a forward Stepwise Multiple Logistic Regression were made to identify predictive factors of burnout. Besides reporting more job strain (in particular job control p = 0.02), higher levels of anxiety (p<0.001), and sleep disorders related to insomnia (OR = 21.5, 95%CI = 8.8–52.3), participants with burnout presented higher levels of HbA1C, glycaemia, CRP, lower levels of 25(OH)D, higher number of leukocytes, neutrophils and monocytes (P<0.001 for all) and higher total-cholesterol (P = 0.01). In particular, when HbA1c is > 3.5%, the prevalence of burnout increases from 16.6% to 60.0% (OR = 4.3, 95%CI = 2.8–6.9). Strong significant positive correlation existed between HbA1C and the two dimensions (emotional exhaustion and depersonalization (r = 0.79 and r = 0.71, p<0.01)) of burnout. Models including job strain, job satisfaction, anxiety and insomnia did not predict burnout (p = 0.30 and p = 0.50). However, when HbA1C levels is included, the prediction of burnout became significant (P = 0.03). Our findings demonstrated the interest of sleep and biological parameters, in particular HbA1C levels, in the characterization of professional burnout. [ABSTRACT FROM AUTHOR]

This European guideline for the diagnosis and treatment of insomnia was developed by a task force of the European Sleep Research Society, with the aim of providing clinical recommendations for the management of adult patients with insomnia. The guideline is based on a systematic review of relevant meta-analyses published till June 2016. The target audience for this guideline includes all clinicians involved in the management of insomnia, and the target patient population includes adults with chronic insomnia disorder. The GRADE (Grading of Recommendations Assessment, Development and Evaluation) system was used to grade the evidence and guide recommendations. The diagnostic procedure for insomnia, and its co-morbidities, should include a clinical interview consisting of a sleep history (sleep habits, sleep environment, work schedules, circadian factors), the use of sleep questionnaires and sleep diaries, questions about somatic and mental health, a physical examination and additional measures if indicated (i.e. blood tests, electrocardiogram, electroencephalogram; strong recommendation, moderate- to high-quality evidence). Polysomnography can be used to evaluate other sleep disorders if suspected (i.e. periodic limb movement disorder, sleep-related breathing disorders), in treatment-resistant insomnia, for professional at-risk populations and when substantial sleep state misperception is suspected (strong recommendation, high-quality evidence). Cognitive behavioural therapy for insomnia is recommended as the first-line treatment for chronic insomnia in adults of any age (strong recommendation, high-quality evidence). A pharmacological intervention can be offered if cognitive behavioural therapy for insomnia is not sufficiently effective or not available. Benzodiazepines, benzodiazepine receptor agonists and some antidepressants are effective in the short-term treatment of insomnia (≤4 weeks; weak recommendation, moderate-quality evidence). Antihistamines, antipsychotics, melatonin and phytotherapeutics are not recommended for insomnia treatment (strong to weak recommendations, low- to very-low-quality evidence). Light therapy and exercise need to be further evaluated to judge their usefulness in the treatment of insomnia (weak recommendation, low-quality evidence). Complementary and alternative treatments (e.g. homeopathy, acupuncture) are not recommended for insomnia treatment (weak recommendation, very-low-quality evidence). [ABSTRACT FROM AUTHOR]

Background: Sleep disorders are often underreported to physicians by patients with allergies. This study aimed to characterize the sleep disorders associated with respiratory allergy to house dust mites (HDM) at the time of initiation of sublingual allergen immunotherapy (SLIT) in routine clinical practice. Methods: This prospective, cross-sectional, observational study was conducted between November 2014 and March 2015 at 189 French trial sites and included 1750 participants suffering from HDM allergy who were initiating SLIT. Participants aged less than 5 years old and those who had previously started an allergen immunotherapy (AIT) for HDM allergy were not enrolled in the study. Sleep disorders were assessed by self-administered questionnaires: the Epworth Sleepiness Scale (ESS), the Insomnia Severity Index (ISI) and a modified version of the Hotel Dieu-42 (HD-42) sleep disorder questionnaire. Logistic regression models adjusted for obesity, smoking status, asthma control and nasal obstruction were used to study the relationship between allergic rhinitis (AR) classification and sleep disorders/ complaints. Results: Of the 1786 participants enrolled, 1750 (907 adults and 843 children) composed the analysis population. The majority of participants (73.5% of adults and 65.8% of children) reported that their sleep disorders had prompted them to consult their physician. The most commonly observed sleep complaints were poor-quality sleep (50.3% of adults and 37.3% of children), snoring (48.1 and 41.4%, respectively) and nocturnal awakening (37.6 and 28.2%, respectively). Difficulties falling asleep were reported by 27.0% of adults and 24.7% of children. Adults and children suffering from severe persistent AR experienced sleep complaints significantly more often than participants with intermittent or mild persistent AR. Conclusions: This study highlights the high frequency of sleep disorders and their significant impact on patients with AR induced by HDM, in particular when AR is persistent and severe. Consequently, asking allergic patients about the quality of their sleep appears to be important, especially when the patient has persistent and severe AR. [ABSTRACT FROM AUTHOR]

Abstract: Background: Light is a powerful synchronizer of the biological clock and of the sleep/wake cycle. Blind people have more sleep disturbances than people without eyesight problems. However, whether visually able people who are underexposed to bright natural light suffer from sleep wake disorders has never been examined. This study tried to assess the prevalence of sleep and wake disorders in subjects working in environments that are not exposed to natural light. Methodology: A setting–controlled cross–sectional epidemiological study was carried out. A representative sample of 13 296 French employees of a single transportation company participated in the study. During working hours, 4635 subjects (34.9%) experienced no light exposure (NLE) and 8661 were partially or completely exposed (LE) to natural light. Sleep disorders, sleep quality, and sleepiness were assessed using subjective tools: the Sleep Disorders Questionnaire–French version (SDQFV) and the Epworth Sleepiness Scale (ESS). Light exposure was estimated on workers'' schedules and by objective measurements of light intensity (lux meter). Principal findings: On a univariate analysis, complaints of poor sleep and sleepiness were significantly higher in NLE workers compared to LE: nonrestorative sleep (36.8% vs. 29.5%; P<.0001), insomnia (28.8% vs. 24.8%; P<.0001), severe insomnia (14.1% vs. 10.9%; P<.0001), and daytime somnolence (6.8% vs. 4.3%; P<.0001). After multivariate analysis, NLE has shown more insomnia (OR=1.8, 95% CI 1.3–2.3, P<.01) and hypersomnia (OR=1.9, 95% CI=1.3–2.4, P<.01) than LE. Significance: These data suggest that underexposure to natural light at work may significantly impair sleep and wake disorders in non–light-exposed workers. [Copyright &y& Elsevier]

: PurposeMelatonin, which is produced by the pineal gland at night, is an endogenous sleep regulator. Both sleep disorders and impaired melatonin production are common among the elderly. We examined the excretion of the major melatonin metabolite 6-sulfatoxymelatonin in insomnia patients aged ≥55 years and its relation with the subsequent response to melatonin therapy.: MethodsWe studied 517 insomnia patients, along with 29 age-matched and 30 younger healthy volunteers. Nocturnal urinary 6-sulfatoxymelatonin excretion was assessed between 10 pm and 10 am. Three hundred and ninety-six of the insomnia patients were treated for 2 weeks with placebo and for 3 weeks with 2 mg per night of controlled-release melatonin, of which 372 provided complete datasets. Clinical response, assessed with the Leeds Sleep Evaluation Questionnaire, was defined as an improvement of 10 mm or more on the visual analog scales.: ResultsMean (± SD) 6-sulfatoxymelatonin excretion was lower in the insomnia patients (9.0 ± 8.3 μg per night) than in volunteers of the same age (18.1 ± 12.7 μg per night, P <0.05) and in younger volunteers (24.2 ± 11.9 μg per night, P <0.05). About 30% of patients (112/372) excreted ≤3.5 μg of sulfatoxymelatonin per night, which is considered to be lower than normal for this age group. These “low excretors” had a significantly higher response to melatonin replacement therapy (58% [65/112] vs. 47% [122/260], P <0.05).: ConclusionLow nocturnal melatonin production is associated with insomnia in patients aged 55 years or older, and identifies patients who are somewhat more likely to respond to melatonin replacement. [Copyright &y& Elsevier]

This study was an epidemiological questionnaire survey of a representative sample of the French population that included 12 778 individuals and in which adapted DSM-IV criteria for the definition of insomnia were used. Our goals were not only to assess the prevalence of ‘insomnia’ using these criteria, but also to compare the results obtained with those of prior studies using different definitions of ‘insomnia’. The aim of this study was also to identify where areas of agreement and disaggreement existed, as we believe that it is important to emphasize these points because DSM-IV recommendations are supposedly reflected in clinical practice. Seventy-three per cent of the individuals surveyed complained of a nocturnal sleep problem, but only 29% reported at least one sleep problem three times per week for a month, and 19% (2428 subjects) had at least one sleep problem three times per week for a month and complained of daytime consequences (DSM-IV criteria). Only 9% had two or more nocturnal sleep problems with daytime consequences and were classified as ‘severe insomniacs’. Our study indicates that if DSM-IV criteria are used, the diagnosis of ‘insomnia’ is lower than in other epidemiological studies. The DSM criteria have an advantage in that they emphasize the daytime consequences of nocturnal sleep disturbances, which seem to be responsible for the most important socio-economic costs of the problem. [ABSTRACT FROM AUTHOR]

There is evidence of a strong association between insomnia and COVID-19, yet few studies have examined the relationship between insomnia and long COVID. This study aimed to investigate whether COVID-19 patients with pre-pandemic insomnia have a greater risk of developing long COVID and whether long COVID is in turn associated with higher incident rates of insomnia symptoms after infection. Data were collected cross-sectionally (May–Dec 2021) as part of an international collaborative study involving participants from 16 countries. A total of 2311 participants (18–99 years old) with COVID-19 provided valid responses to a web-based survey about sleep, insomnia, and health-related variables. Log-binomial regression was used to assess bidirectional associations between insomnia and long COVID. Analyses were adjusted for age, sex, and health conditions, including sleep apnea, attention and memory problems, chronic fatigue, depression, and anxiety. COVID-19 patients with pre-pandemic insomnia showed a higher risk of developing long COVID than those without pre-pandemic insomnia (70.8% vs 51.4%; adjusted relative risk [RR]: 1.33, 95% confidence interval [CI]: 1.07–1.65). Among COVID-19 cases without pre-pandemic insomnia, the rates of incident insomnia symptoms after infection were 24.1% for short COVID cases and 60.6% for long COVID cases (p <.001). Compared with short COVID cases, long COVID cases were associated with an increased risk of developing insomnia symptoms (adjusted RR: 2.00; 95% CI: 1.50–2.66). The findings support a bidirectional relationship between insomnia and long COVID. These findings highlight the importance of addressing sleep and insomnia in the prevention and management of long COVID. • COVID-19 patients with pre-pandemic insomnia showed a higher risk of developing long COVID than those without pre-pandemic insomnia. • Among COVID-19 cases without pre-pandemic insomnia, the rates of incident insomnia symptoms after infection were 24.1% for short COVID cases and 60.6% for long COVID cases. • The findings support a bidirectional relationship between insomnia and long COVID, which highlights the importance of addressing sleep and insomnia in the prevention and management of long COVID. [ABSTRACT FROM AUTHOR]

Background: Daytime functioning is impaired in people with insomnia disorder. Currently available dual orexin receptor antagonists have shown efficacy in insomnia disorder, but do not address all aspects of this disease. We aimed to assess safety and efficacy of daridorexant, a novel orexin receptor antagonist, on night-time and daytime symptoms of insomnia.Methods: We did two multicentre, randomised, double-blind, placebo-controlled, phase 3 trials at 156 sites in 17 countries. Adults (aged ≥18 years) with insomnia disorder were randomly assigned using interactive response technology (1:1:1) to receive daridorexant 50 mg, 25 mg, or placebo (study 1) or daridorexant 25 mg, 10 mg, or placebo (study 2) every evening for 3 months. Participants, investigators, and site personnel were masked to treatment allocation. The primary endpoints were change from baseline in wake time after sleep onset (WASO) and latency to persistent sleep (LPS), measured by polysomnography, at months 1 and 3. The secondary endpoints were change from baseline in self-reported total sleep time and the sleepiness domain score of the Insomnia Daytime Symptoms and Impacts Questionnaire (IDSIQ) at months 1 and 3. Study-wise type I error rate (5%) was controlled for all pairwise comparisons. Efficacy was analysed in all randomly assigned participants, and safety in all participants who received at least one dose of treatment. The studies are registered at ClinicalTrials.gov, NCT03545191 (study 1) and NCT03575104 (study 2).Findings: Between June 4, 2018 and Feb 25, 2020, 930 participants were randomly assigned to receive daridorexant 50 mg (n=310), daridorexant 25 mg (n=310), or placebo (n=310) in study 1. Between May 29, 2018, and May 14, 2020, 924 participants were randomly assigned to receive daridorexant 25 mg (n=309), daridorexant 10 mg (n=307), or placebo (n=308) in study 2. In study 1, WASO and LPS were significantly reduced among participants in the daridorexant 50 mg group compared with participants in the placebo group at month 1 (least squares mean [LSM] difference -22·8 min [95% CI -28·0 to -17·6], p<0·0001 for WASO; -11·4 min [-16·0 to -6·7], p<0·0001 for LPS) and month 3 (-18·3 min [-23·9 to -12·7], p<0·0001 for WASO; -11·7 min [-16·3 to -7·0], p<0·0001 for LPS). WASO and LPS were significantly reduced among participants in the daridorexant 25 mg group compared with the placebo group at month 1 (LSM difference -12·2 min [-17·4 to -7·0], p<0·0001 for WASO; -8·3 min [-13·0 to -3·6], p=0·0005 for LPS) and month 3 (-11·9 min [-17·5 to -6·2], p<0·0001 for WASO; -7·6 min [-12·3 to -2·9], p=0·0015 for LPS). Compared with placebo, participants in the daridorexant 50 mg group had significantly improved self-reported total sleep time at month 1 (LSM difference 22·1 min [14·4 to 29·7], p<0·0001) and month 3 (19·8 min [10·6 to 28·9], p<0·0001), and IDSIQ sleepiness domain scores at month 1 (-1·8 [-2·5 to -1·0], p<0·0001) and month 3 (-1·9 [-2·9 to -0·9], p=0·0002). Compared with the placebo group, participants in the daridorexant 25 mg group had significantly improved self-reported total sleep time at month 1 (LSM difference 12·6 min [5·0 to 20·3], p=0·0013) and month 3 (9·9 min [0·8 to 19·1], p=0·033), but not IDSIQ sleepiness domain scores (-0·8 [-1·5 to 0·01], p=0·055 at month 1; -1·0 [-2·0 to 0·01], p=0·053 at month 3). In study 2, WASO was significantly reduced among participants in the daridorexant 25 mg group compared with participants in the placebo group at month 1 (LSM difference -11·6 min [-17·6 to -5·6], p=0·0001) and month 3 (-10·3 min [-17·0 to -3·5], p=0·0028), whereas no significant differences in LPS were observed at month 1 (-6·5 min [-12·3 to -0·6], p=0·030) or month 3 (-9·0 [-15·3 to -2·7], p=0·0053). Compared with the placebo group, participants in the daridorexant 25 mg group had significant improvement in self-reported total sleep time at month 1 (LSM difference 16·1 min [8·2 to 24·0], p<0·0001) and month 3 (19·1 [10·1 to 28·0], p<0·0001), but not in IDSIQ sleepiness domain scores (-0·8 [-1·6 to 0·1], p=0·073 at month 1; -1·3 [-2·2 to -0·3], p=0·012 at month 3). Compared with the placebo group, no significant differences were observed among participants in the daridorexant 10 mg group for WASO (LSM difference -2·7 min [-8·7 to 3·2], p=0·37 at month 1; -2·0 [-8·7 to 4·8], p=0·57 at month 3), LPS (-2·6 min [-8·4 to 3·2], p=0·38 at month 1; -3·2 min [-9·5 to 3·1], p=0·32 at month 3), self-reported total sleep time (13·4 min [5·5 to 21·2], p=0·0009 at month 1; 13·6 min [4·7 to 22·5], p=0·0028 at month 3), nor IDSIQ sleepiness domain scores (-0·4 [-1·3 to 0·4], p=0·30 at month 1; -0·7 [-1·7 to 0·2], p=0·14 at month 3). Overall incidence of adverse events was comparable between treatment groups (116 [38%] of 308 participants in the daridorexant 50 mg group, 117 [38%] of 310 in the daridorexant 25 mg group, and 105 [34%] of 309 in the placebo group in study 1; 121 [39%] of 308 participants in the daridorexant 25 mg group, 117 [38%] of 306 in the daridorexant 10 mg group, and 100 [33%] of 306 in the placebo group). Nasopharyngitis and headache were the most common adverse events in all groups. One death (cardiac arrest) occurred in the daridorexant 25 mg group in study 1, which was not deemed to be treatment-related.Interpretation: Daridorexant 25 mg and 50 mg improved sleep outcomes, and daridorexant 50 mg also improved daytime functioning, in people with insomnia disorder, with a favourable safety profile.Funding: Idorsia Pharmaceuticals. [ABSTRACT FROM AUTHOR]

Abstract: This prospective study aimed to assess symptomatic evolution of patients diagnosed with Upper Airway Resistance Syndrome (UARS) four and half years after the initial UARS diagnosis. For this purpose, 138 UARS patients were contacted by mail between 43 and 69 months after the initial evaluation; 105 responded to the letter and 94 patients accepted to undergo new clinical and polysomnographic evaluations. Initial and follow-up polysomnographic recordings were scored using the same criteria. Results: Of the 94 patients who completed the follow-up examination, none of them were using nasal CPAP. It was related to refusal by insurance providers to provide equipment based on initial apnea–hypopnea index (AHI) in 90/94 subjects. Percentage of patients with sleep related-complaints significantly increased over the four and half year period: daytime fatigue, insomnia and depressive mood increased by 12 to 20 times. Reports of sleep maintenance sleep onset insomnia and depressive mood was significantly increased. Hypnotic, antidepressant and stimulant prescription increased from initial to follow-up visit (from 11.7% to 61.7%; from 3.2% to 25.5% and from 0% to 9.6%, respectively) with antidepressant given as much for sleep disturbance as mood disorder. The polysomnography results at follow-up showed that 5 subjects had AHI compatible with Obstructive Sleep Apnea Syndrome (OSAS) but overall, respiratory disturbance index had no significant change. Total sleep time was significantly reduced compared to initial visit. Conclusions: Many UARS patients remained untreated following initial evaluation. Worsening of symptoms of insomnia, fatigue and depressive mood were seen with absence of treatment of UARS. [Copyright &y& Elsevier]

Abstract: Objective/background: To explore the association between sleep duration and daily caffeine intake in a working population. Caffeine acutely disrupts sleep in the laboratory, but the inter-relations between sleep and caffeine intake in daily life are ill-known. Methods: Questionnaire and diary based survey of 1498 persons from the GAZEL cohort of employees of the National Electricity and Gas Company (EDF-GDF) working in various locations in the Paris and South-West France areas. We analyzed total sleep time, our primary measure, and time in bed, both by sleep logs. We assessed daily intake of caffeine, consumption of alcohol and tobacco, use of hypnotics, and daytime somnolence, all by questionnaire. Results: Multiple linear regression analysis did not find a significant relationship between total sleep time and daily caffeine intake less than 8 cups of coffee per day, after controlling for age, gender, alcohol intake, smoking status, and use of hypnotics. By contrast, time in bed was reduced as caffeine intake increased (β=−0.125; P&#60;0.001). Higher caffeine intake was not related to a higher daytime somnolence. Conclusion: Despite the well-known acute effects of caffeine on sleep, habitual use of up to 7 cups of coffee (or 600mg of caffeine equivalent) per day was not associated with decreased duration of sleep. [Copyright &y& Elsevier]