Associations between obesity, a composite risk score for probable long COVID, and sleep problems in SARS-CoV-2 vaccinated individuals.

BACKGROUND: Preliminary data suggests that obesity might hasten the decline in mRNA vaccine-induced immunity against SARS-CoV-2. However, whether this renders individuals with obesity more susceptible to long COVID symptoms post-vaccination remains uncertain. Given sleep's critical role in immunity, exploring the associations between obesity, probable long COVID symptoms, and sleep disturbances is essential. METHODS: We analyzed data from a survey of 5919 adults aged 18 to 89, all of whom received two SARS-CoV-2 mRNA vaccinations. Participants were categorized into normal weight, overweight, and obesity groups based on ethnicity-specific BMI cutoffs. The probability of long COVID was evaluated using the Post-Acute Sequelae of SARS-CoV-2 (PASC) score, as our survey did not permit confirmation of acute SARS-CoV-2 infection through methods such as antibody testing. Additionally, sleep patterns were assessed through questionnaires. RESULTS: Participants with obesity exhibited a significantly higher adjusted odds ratio (OR) of having a PASC score of 12 or higher, indicative of probable long COVID in our study, compared to those with normal weight (OR: 1.55, 95% CI: 1.05, 2.28). No significant difference was observed for overweight individuals (OR: 0.92 [95% CI: 0.63, 1.33]). Both obesity and probable long COVID were associated with increased odds of experiencing a heightened sleep burden, such as the presence of obstructive sleep apnea or insomnia (P < 0.001). However, no significant interaction between BMI and probable long COVID status was found. CONCLUSIONS: Even post-vaccination, individuals with obesity may encounter a heightened risk of experiencing prolonged COVID-19 symptoms. However, confirming our observations necessitates comprehensive studies incorporating rigorous COVID infection testing, such as antibody assays - unavailable in our anonymous survey. Additionally, it is noteworthy that the correlation between probable long COVID and sleep disturbances appears to be independent of BMI.

Nightmare frequency is a risk factor for suicidal ideation during the COVID-19 pandemic.

The association between nightmare frequency (NMF) and suicidal ideation (SI) is well known, yet the impact of the COVID-19 pandemic on this relation is inconsistent. This study aimed to investigate changes in NMF, SI, and their association during the COVID-19 pandemic. Data were collected in 16 countries using a harmonised questionnaire. The sample included 9328 individuals (4848 women; age M[SD] = 46.85 [17.75] years), and 17.60% reported previous COVID-19. Overall, SI was significantly 2% lower during the pandemic vs. before, and this was consistent across genders and ages. Most countries/regions demonstrated decreases in SI during this pandemic, with Austria (-9.57%), Sweden (-6.18%), and Bulgaria (-5.14%) exhibiting significant declines in SI, but Italy (1.45%) and Portugal (2.45%) demonstrated non-significant increases. Suicidal ideation was more common in participants with long-COVID (21.10%) vs. short-COVID (12.40%), though SI did not vary by COVID-19 history. Nightmare frequency increased by 4.50% during the pandemic and was significantly higher in those with previous COVID-19 (14.50% vs. 10.70%), during infection (23.00% vs. 8.10%), and in those with long-COVID (18.00% vs. 8.50%). The relation between NMF and SI was not significantly stronger during the pandemic than prior (rs = 0.18 vs. 0.14; z = 2.80). Frequent nightmares during the pandemic increased the likelihood of reporting SI (OR = 1.57, 95% CI 1.20-2.05), while frequent dream recall during the pandemic served a protective effect (OR = 0.74, 95% CI 0.59-0.94). These findings have important implications for identifying those at risk of suicide and may offer a potential pathway for suicide prevention.

Association of poor sleep and HbA1c in metformin-treated patients with type 2 diabetes: Findings from the UK Biobank cohort study.

The American Diabetes Association recommends a glycated haemoglobin target of less than 7% for treating type 2 diabetes mellitus. However, it is still being determined if poor sleep affects this therapeutic goal, despite being treated with the blood-glucose-lowering medication metformin. Thus, we used data from 5703 patients on metformin monotherapy participating in the UK Biobank baseline investigation between 2006 and 2010. We combined self-reported chronotype, daily sleep duration, insomnia, daytime sleepiness and snoring into a multidimensional poor sleep score ranging from 0 to 5, with higher scores indicating a less healthy sleep pattern. With each point increase on the poor sleep score scale, the odds of patients having an glycated haemoglobin of ≥ 7% increased by 6% (odds ratio [95% confidence interval], 1.06 [1.01, 1.11], p = 0.021). When examining the components of the poor sleep score separately, snoring was specifically associated with a glycated haemoglobin of ≥ 7% (1.12 [1.01, 1.25] versus no snoring, p = 0.038). However, adjusting for health and lifestyle conditions, such as body mass index, weekly physical activity level and hypertension status, eliminated the significant associations between the poor sleep score and snoring with glycated haemoglobin of ≥ 7%. Our findings suggest that poor sleep, specifically snoring, a symptom of obstructive sleep apnea, may interfere with the therapeutic goal of achieving a glycated haemoglobin below 7%. However, other factors known to be promoted by poor sleep, such as high body mass index, low physical activity and hypertension, may also contribute to the link between poor sleep and higher glycated haemoglobin levels.

A useful tool or a new challenge? Hand-wrist-worn sleep trackers in patients with insomnia.

Consumer sleep wearables are increasingly popular, even among patients with sleep problems. However, the daily feedback provided by these devices could exacerbate sleep-related worry. To investigate this issue, 14 patients received a self-help guide booklet to improve sleep and wore the sleep tracker Fitbit Inspire 2 on their non-dominant hand for 4 weeks, while a control group of 12 patients only kept a handwritten sleep diary. All patients completed questionnaires at a primary care centre's first and final visit to assess general anxiety, sleep quality, sleep reactivity to stress, and quality of life. Our analysis showed that sleep quality, sleep reactivity to stress, and quality of life improved significantly for all patients between the first and final visit (p < 0.05). However, there were no significant differences between the Fitbit and control groups. Using sleep diary-derived estimates from the first and last week, we found that the control group but not the Fitbit group, increased their average time asleep each night and sleep efficiency (p < 0.05). However, these differences were primarily driven by baseline differences between the two groups. Our findings suggest that using wearables does not necessarily exacerbate sleep worries among people with insomnia.

A weighted blanket increases pre-sleep salivary concentrations of melatonin in young, healthy adults.

Weighted blankets have emerged as a potential non-pharmacological intervention to ease conditions such as insomnia and anxiety. Despite a lack of experimental evidence, these alleged effects are frequently attributed to a reduced activity of the endogenous stress systems and an increased release of hormones such as oxytocin and melatonin. Thus, the aim of the present in-laboratory crossover study (26 young and healthy participants, including 15 men and 11 women) was to investigate if using a weighted blanket (~12% of body weight) at bedtime resulted in higher salivary concentrations of melatonin and oxytocin compared with a light blanket (~2.4% of body weight). We also examined possible differences in salivary concentrations of the stress hormone cortisol, salivary alpha-amylase activity (as an indicative metric of sympathetic nervous system activity), subjective sleepiness, and sleep duration. When using a weighted blanket, the 1 hour increase of salivary melatonin from baseline (i.e., 22:00) to lights off (i.e., 23:00) was about 32% higher (p = 0.011). No other significant differences were found between the blanket conditions, including subjective sleepiness and total sleep duration. Our study is the first to suggest that using a weighted blanket may result in a more significant release of melatonin at bedtime. Future studies should investigate whether the stimulatory effect on melatonin secretion is observed on a nightly basis when frequently using a weighted blanket over weeks to months. It remains to be determined whether the observed increase in melatonin may be therapeutically relevant for the previously described effects of the weighted blanket on insomnia and anxiety.

Sleep symptoms are essential features of long-COVID - Comparing healthy controls with COVID-19 cases of different severity in the international COVID sleep study (ICOSS-II).

Many people report suffering from post-acute sequelae of COVID-19 or "long-COVID", but there are still open questions on what actually constitutes long-COVID and how prevalent it is. The current definition of post-acute sequelae of COVID-19 is based on voting using the Delphi-method by the WHO post-COVID-19 working group. It emphasizes long-lasting fatigue, shortness of breath and cognitive dysfunction as the core symptoms of post-acute sequelae of COVID-19. In this international survey study consisting of 13,628 subjects aged 18-99 years from 16 countries of Asia, Europe, North America and South America (May-Dec 2021), we show that post-acute sequelae of COVID-19 symptoms were more prevalent amongst the more severe COVID-19 cases, i.e. those requiring hospitalisation for COVID-19. We also found that long-lasting sleep symptoms are at the core of post-acute sequelae of COVID-19 and associate with the COVID-19 severity when COVID-19 cases are compared with COVID-negative cases. Specifically, fatigue (61.3%), insomnia symptoms (49.6%) and excessive daytime sleepiness (35.8%) were highly prevalent amongst respondents reporting long-lasting symptoms after hospitalisation for COVID-19. Understanding the importance of sleep-related symptoms in post-acute sequelae of COVID-19 has a clinical relevance when diagnosing and treating long-COVID.

Association of socioeconomic deprivation with sleep health in patients with type 2 diabetes.

AIMS: To investigate the association between socioeconomic deprivation and indicators of sleep health among patients with type 2 diabetes mellitus (T2DM), and additionally, to examine whether socioeconomic deprivation is associated with higher glycated haemoglobin (HbA1c) levels in these patients. MATERIALS AND METHODS: We analysed data from the UK Biobank, consisting of 17 206 participants with T2DM, to explore the relationship between socioeconomic deprivation, self-reported indicators of sleep health, and HbA1c levels. Socioeconomic deprivation was assessed using the Townsend deprivation index. Participants were divided into two groups: low socioeconomic deprivation (n = 8604; reference group) and high socioeconomic deprivation (n = 8602). Logistic regression models were employed, adjusting for covariates such as body mass index (BMI), age, and biological sex. RESULTS: Patients with high socioeconomic deprivation had higher odds of reporting usual difficulties falling asleep or sleeping through the night (adjusted odds ratio 1.20, 95% confidence interval [CI] 1.12, 1.28), and they were more likely to use at least one hypnotic medication (adjusted odds ratio 1.41, 95% CI 1.09, 1.84). They also had higher odds of reporting snoring and difficulties staying awake during the daytime (adjusted odds ratio 1.09, 95% CI 1.01, 1.18), as well as experiencing short sleep duration (defined as <6 hours of sleep per day; adjusted odds ratio 1.69, 95% CI 1.50, 1.91). Moreover, patients with high socioeconomic deprivation had increased odds of experiencing comorbid sleep problems (P ≤ 0.001). Finally, high socioeconomic deprivation was associated with a 0.1% higher HbA1c level (P < 0.001). Controlling for indicators of poor sleep health did not alter the strength of this association. CONCLUSIONS: Socioeconomic deprivation may represent a risk factor for poor sleep health in patients with T2DM.

Objective sleep characteristics and continuous glucose monitoring profiles of type 2 diabetes patients in real-life settings.

AIM: To investigate the association between objective sleep parameters and glycaemic variability determined by continous glucose monitoring (CGM) among patients with type 2 diabetes, given the significant role of sleep in glycaemic control. METHODS: In this study, CGM was carried out in 28 patients with T2D (aged 62.3 ± 4.8 years, 57% women). Sleep characteristics were assessed by actigraphy within the CGM period. CGM-derived outcomes included glucose level, and percentages of time in range (TIR) and time above range (TAR) during the monitoring period. Associations between intraindividual night-to-night variations in sleep characteristics and overall CGM outcomes were analysed using linear regression. Associations between sleep characteristics during each night and time-matched CGM outcomes were analysed using linear mixed models. RESULTS: A total of 249 person-days of CGM, coupled with 221 nights of sleep characteristics, were documented. Greater standard deviation (SD) of objective sleep duration (minutes) between measurement nights was associated with higher glucose level (coefficient 0.018 mmol/L [95% confidence interval {CI} 0.004, 0.033], P = 0.017), smaller proportion of TIR (% in observation period; coefficient -0.20% [95% CI -0.36, -0.03], P = 0.023), and greater proportion of TAR (coefficient 0.22% [95% CI 0.06, 0.39], P = 0.011). Later sleep midpoint (minutes from midnight) was associated with greater SD of glucose during the same sleep period (coefficient 0.002 minutes [95% CI 0.0001, 0.003], P = 0.037), longer nocturnal sleep duration was associated with smaller coefficient of variation of glucose level in the upcoming day (-0.015% [95% CI -0.03, -0.001], P = 0.041). CONCLUSION: Objectively determined sleep duration and sleep midpoint, as well as their daily variability, are associated with CGM-derived glucose profiles in T2D patients.

Associations between changes in habitual sleep duration and lower self-rated health among COVID-19 survivors: findings from a survey across 16 countries/regions.

BACKGROUND: Self-rated health (SRH) is widely recognized as a clinically significant predictor of subsequent mortality risk. Although COVID-19 may impair SRH, this relationship has not been extensively examined. The present study aimed to examine the correlation between habitual sleep duration, changes in sleep duration after infection, and SRH in subjects who have experienced SARS-CoV-2 infection. METHODS: Participants from 16 countries participated in the International COVID Sleep Study-II (ICOSS-II) online survey in 2021. A total of 10,794 of these participants were included in the analysis, including 1,509 COVID-19 individuals (who reported that they had tested positive for COVID-19). SRH was evaluated using a 0-100 linear visual analog scale. Habitual sleep durations of < 6 h and > 9 h were defined as short and long habitual sleep duration, respectively. Changes in habitual sleep duration after infection of ≤ -2 h and ≥ 1 h were defined as decreased or increased, respectively. RESULTS: Participants with COVID-19 had lower SRH scores than non-infected participants, and those with more severe COVID-19 had a tendency towards even lower SRH scores. In a multivariate regression analysis of participants who had experienced COVID-19, both decreased and increased habitual sleep duration after infection were significantly associated with lower SRH after controlling for sleep quality (ß = -0.056 and -0.058, respectively, both p < 0.05); however, associations between current short or long habitual sleep duration and SRH were negligible. Multinomial logistic regression analysis showed that decreased habitual sleep duration was significantly related to increased fatigue (odds ratio [OR] = 1.824, p < 0.01), shortness of breath (OR = 1.725, p < 0.05), diarrhea/nausea/vomiting (OR = 2.636, p < 0.01), and hallucinations (OR = 5.091, p < 0.05), while increased habitual sleep duration was significantly related to increased fatigue (OR = 1.900, p < 0.01). CONCLUSIONS: Changes in habitual sleep duration following SARS-CoV-2 infection were associated with lower SRH. Decreased or increased habitual sleep duration might have a bidirectional relation with post-COVID-19 symptoms. Further research is needed to better understand the mechanisms underlying these relationships for in order to improve SRH in individuals with COVID-19.

Seasonal variations in sleep duration and sleep complaints: A Swedish cohort study in middle-aged and older individuals.

Subjective sleep reports are widely used research tools in epidemiology. Whether sleep reports can differ between seasons is less clear. Using multivariable binary or multinomial logistic regression analyses, in the present Swedish cross-sectional two-centre cohort study (N = 19,254; mean age 61 years), we found that participants surveyed during the summer (June-August) were more likely to report short sleep duration (defined as ≤ 6 hr) compared with those interviewed during the autumn (odds ratio [95% confidence interval] = 1.14 [1.04-1.25]). Individuals interviewed in the winter (December-February) were less likely to report early awakenings compared with participants surveyed in the autumn (September-November; odds ratio [95% confidence interval] = 0.85 [0.75-0.96]). Complaints of difficulties in falling asleep and disturbed sleep were less common among participants interviewed during spring (March-May) compared with those interviewed during the autumn (odds ratio [95% confidence interval] = 0.86 [0.74-0.99] and 0.88 [0.79-0.98], respectively). No seasonal variations in reports of long sleep, difficulty maintaining sleep, or feeling not rested after sleep were observed. Additional subgroup analysis revealed that summer participants were more likely to report short sleep duration and early morning awakenings than individuals surveyed in winter. In conclusion, this Swedish study indicates that self-reported sleep characteristics may vary across seasons. Further studies are needed to confirm our findings.

Acute sleep loss alters circulating fibroblast growth factor 21 levels in humans: A randomised crossover trial.

The hormone fibroblast growth factor 21 (FGF21) modulates tissue metabolism and circulates at higher levels in metabolic conditions associated with chronic sleep-wake disruption, such as type 2 diabetes and obesity. In the present study, we investigated whether acute sleep loss impacts circulating levels of FGF21 and tissue-specific production, and response pathways linked to FGF21. A total of 15 healthy normal-weight young men participated in a randomised crossover study with two conditions, sleep loss versus an 8.5-hr sleep window. The evening before each intervention, fasting blood was collected. Fasting, post-intervention morning skeletal muscle and adipose tissue samples underwent quantitative polymerase chain reaction and DNA methylation analyses, and serum FGF21 levels were measured before and after an oral glucose tolerance test. Serum levels of FGF21 were higher after sleep loss compared with sleep, both under fasting conditions and following glucose intake (~27%-30%, p = 0.023). Fasting circulating levels of fibroblast activation protein, a protein which can degrade circulating FGF21, were not altered by sleep loss, whereas DNA methylation in the FGF21 promoter region increased only in adipose tissue. However, even though specifically the muscle exhibited transcriptional changes indicating adverse alterations to redox and metabolic homeostasis, no tissue-based changes were observed in expression of FGF21, its receptors, or selected signalling targets, in response to sleep loss. In summary, we found that acute sleep loss resulted in increased circulating levels of FGF21 in healthy young men, which may occur independent of a tissue-based stress response in metabolic peripheral tissues. Further studies may decipher whether changes in FGF21 signalling after sleep loss modulate metabolic outcomes associated with sleep or circadian disruption.

No association between a common type 2 diabetes risk gene variant in the melatonin receptor gene (MTNR1B) and mortality among type 2 diabetes patients.

The minor G risk allele in the common melatonin receptor gene (MTNR1B, rs10830963) has been associated with an increased risk of myocardial infarction among patients with type 2 diabetes (T2D). Furthermore, activating the melatonin receptor 1B through melatonin has been shown to promote cell proliferation, which could be hypothesized to increase cancer risk. Cardiovascular disease (CVD) and cancer are common causes of death among patients with T2D. Using data from 14 736  patients with T2D who participated in the UK Biobank investigation, we hypothesized an additive effect of the G risk allele on all-cause mortality, CVD mortality, and cancer mortality. As shown by Cox regression adjusted for confounders such as age, glucose-lowering medication, and socioeconomic status, no significant trend between the number of G risk alleles and mortality outcomes was found during the follow-up period of 11.1 years. Our negative findings do not speak against the role of this gene variant in the development of T2D, as repeatedly shown by previous large-scale studies. Instead, they may suggest that rs10830963 is less relevant for mortality risk in patients with T2D.

Impaired procedural memory in narcolepsy type 1.

OBJECTIVES: Sleep enhances the consolidation of memories. Here, we investigated whether sleep-dependent memory consolidation differs between healthy subjects and narcolepsy type 1 (NT1) patients. MATERIAL AND METHODS: We recruited 18 patients with NT1 and 24 healthy controls. The consolidation of spatial (declarative memory; 2-dimensional object location) and procedural (non-declarative memory; finger sequence tapping) memories was examined across one night of at-home sleep. Sleep was measured by an ambulatory sleep recording device. RESULTS: The overnight gain in the number of correctly recalled sequences in the finger-tapping test was smaller for NT1 patients than healthy subjects (+8.1% vs. +23.8% from pre-sleep learning to post-sleep recall, p = .035). No significant group differences were found for the overnight consolidation of spatial memory. Compared to healthy subjects, the sleep of NT1 patients was significantly more fragmented and shallow. However, no significant correlations were found between sleep parameters and overnight performance changes on the memory tests in the whole group. CONCLUSION: The sleep-dependent consolidation of procedural but not spatial memories may be impaired among patients with NT1. Therefore, future studies are warranted to examine whether sleep improvement, for example, using sodium oxybate, can aid the sleep-dependent formation of procedural memories among NT1 patients.

The association between high risk of sleep apnea, comorbidities, and risk of COVID-19: a population-based international harmonized study.

PURPOSE: Obstructive sleep apnea (OSA) may increase the risk of severe COVID-19; however, the level of potential modulation has not yet been established. The objective of the study was to determine the association between high risk of OSA, comorbidities, and increased risk for COVID-19, hospitalization, and intensive care unit (ICU) treatment. METHODS: We conducted a cross-sectional population-based web survey in adults in 14 countries/regions. The survey included sociodemographic variables and comorbidities. Participants were asked questions about COVID-19, hospitalization, and ICU treatment. Standardized questionnaire (STOP questionnaire for high risk of OSA) was included. Multivariable logistic regression was conducted adjusting for various factors. RESULTS: Out of 26,539 respondents, 20,598 (35.4% male) completed the survey. Mean age and BMI of participants were 41.5 ± 16.0 years and 24.0 ± 5.0 kg/m2, respectively. The prevalence of physician-diagnosed OSA was 4.1% and high risk of OSA was 9.5%. We found that high risk of OSA (adjusted odds ratio (aOR) 1.72, 95% confidence interval (CI): 1.20, 2.47) and diabetes (aOR 2.07, 95% CI: 1.23, 3.48) were associated with reporting of a COVID-19 diagnosis. High risk for OSA (aOR 2.11, 95% CI: 1.10-4.01), being male (aOR: 2.82, 95% CI: 1.55-5.12), having diabetes (aOR: 3.93, 95% CI: 1.70-9.12), and having depression (aOR: 2.33, 95% CI: 1.15-4.77) were associated with increased risk of hospitalization or ICU treatment. CONCLUSIONS: Participants at high risk of OSA had increased odds of having COVID-19 and were two times more likely to be hospitalized or treated in ICU.

Bed and rise times during the Age of Enlightenment: A case report.

Studies have shown that our modern electrical lighting environment reduces naturally occurring seasonal variations in sleep-wake rhythms, such as longer sleep during the winter versus summer. However, less is known about how timing and duration of sleep were affected by the seasons in the premodern era, before the invention of electrical lighting. The Swedish researcher Olof Hiorter collected and documented geophysical data every hour during wakefulness in Uppsala, Sweden, between December 1746 and November 1747. In this way, his bed and rise times could be approximated. The data revealed that Hiorter's rise times occurred around 1 hr before sunrise in winter versus 1 hr after sunrise in summer. No such association was observed between the time of sunset and Hiorter's bedtimes. Finally, the time in bed was about 3.5-4 hr shorter in summer compared to winter. This 273-year-old case report suggests that time in bed and rise times of people from the premodern era exhibited seasonal variations.

Acute sleep loss induces signs of visual discomfort in young men.

Acute sleep loss influences visual processes in humans, such as recognizing facial emotions. However, to the best of our knowledge, no study till date has examined whether acute sleep loss alters visual comfort when looking at images. One image statistic that can be used to investigate the level of visual comfort experienced under visual encoding is the slope of the amplitude spectrum, also referred to as the slope constant. The slope constant describes the spatial distribution of pixel intensities and deviations from the natural slope constant can induce visual discomfort. In the present counterbalanced crossover design study, 11 young men with normal or corrected-to-normal vision participated in two experimental conditions: one night of sleep loss and one night of sleep. In the morning after each intervention, subjects performed a computerized psychophysics task. Specifically, they were required to adjust the slope constant of images depicting natural landscapes and close-ups with a randomly chosen initial slope constant until they perceived each image as most natural looking. Subjects also rated the pleasantness of each selected image. Our analysis showed that following sleep loss, higher slope constants were perceived as most natural looking when viewing images of natural landscapes. Images with a higher slope constant are generally perceived as blurrier. The selected images were also rated as less pleasant after sleep loss. No such differences between the experimental conditions were noted for images of close-ups. The results suggest that sleep loss induces signs of visual discomfort in young men. Possible implications of these findings are discussed.

A single night of sleep loss impairs objective but not subjective working memory performance in a sex-dependent manner.

Acute sleep deprivation can lead to judgement errors and thereby increases the risk of accidents, possibly due to an impaired working memory. However, whether the adverse effects of acute sleep loss on working memory are modulated by auditory distraction in women and men are not known. Additionally, it is unknown whether sleep loss alters the way in which men and women perceive their working memory performance. Thus, 24 young adults (12 women using oral contraceptives at the time of investigation) participated in two experimental conditions: nocturnal sleep (scheduled between 22:30 and 06:30 hours) versus one night of total sleep loss. Participants were administered a digital working memory test in which eight-digit sequences were learned and retrieved in the morning after each condition. Learning of digital sequences was accompanied by either silence or auditory distraction (equal distribution among trials). After sequence retrieval, each trial ended with a question regarding how certain participants were of the correctness of their response, as a self-estimate of working memory performance. We found that sleep loss impaired objective but not self-estimated working memory performance in women. In contrast, both measures remained unaffected by sleep loss in men. Auditory distraction impaired working memory performance, without modulation by sleep loss or sex. Being unaware of cognitive limitations when sleep-deprived, as seen in our study, could lead to undesirable consequences in, for example, an occupational context. Our findings suggest that sleep-deprived young women are at particular risk for overestimating their working memory performance.

Self-reported sleep disturbances and prostate cancer morbidity and mortality in Swedish men: A longitudinal study over 40 years.

The present study, with an observational period of about 40 years, examined the association between self-reported sleep disturbances (i.e. problems with falling and staying asleep; use of hypnotics) and prostate cancer morbidity and mortality in initially 2322 men (all 50 years old at baseline). Self-reported sleep disturbances and established risk factors (e.g. age, lower urinary tract symptoms, smoking and family history of cancer) were measured at ages 50 and 70 years. Information about prostate cancer diagnosis and deaths as a result of prostate cancer was available from the National Cancer Registry and the Swedish Civil Registry of Morbidity. During the observational period, 263 participants developed prostate cancer (11% of the total cohort); 146 of them died as a result of prostate cancer. There was no association between sleep disturbances and prostate cancer morbidity or mortality (hazard ratio 1.09, 95% confidence interval (CI) 0.79, 1.52, and hazard ratio 1.21, 95% CI 0.77, 1.91, respectively). Similar findings were observed when examining associations between single sleep disturbance parameters and prostate cancer morbidity and mortality. Our study does not provide evidence that reports of sleep disturbances increase the risk of prostate cancer morbidity or mortality in middle to older-aged men. Therefore, assessing subjective sleep problems may not meaningfully help to identify men at risk of developing prostate cancer or dying of this devastating condition.