[Chemsex : A new challenge in addiction medicine and infectious diseases]. / Chemsex : Eine neue Herausforderung der Suchtmedizin und Infektiologie.

BACKGROUND: Recently there has been an increase in reports of the phenomenon called chemsex, a subform of sexualized substance use. Chemsex is a neologism consisting of the two terms "chemicals" and "sex". It describes the use of methamphetamine, γ­hydroxybutyrate/γ-butyrolactone (GHB/GBL), mephedrone and sometimes other substances in a sexual context, especially by men who have sex with men (MSM). Chemsex has been described as a significant risk factor for mental and physical diseases. OBJECTIVE: Due to the increasing importance of the phenomenon and the significantly increased number of publications on the subject, this article provides an overview of the current and relevant literature. The aim is to raise awareness on this topic among practitioners and researchers and thus to facilitate access to the help system for those affected. METHOD: A literature search was conducted in PubMed/Medline, Cochrane and Embase for the terms "chemsex", "sexualized drug use" and "slamming. A total of 22 articles were identified as being relevant. RESULTS: In the published literature on chemsex the current focus lies on somatic comorbidities. There is a significantly increased risk of sexually transmitted diseases. Mental illnesses such as depression, substance-induced psychosis and addiction also appear to be a significant consequence of chemsex. An individualized and specialized treatment approach is not yet established. DISCUSSION: The complexity of chemsex with its psychiatric and somatic aspects does not yet appear to be sufficiently reflected by the current data situation; however, due to the mutual influence of these different comorbidities, this patient clientele appears to be particularly at risk in the absence of a specialized treatment option, which is why further research on this topic is needed.

Does insufficient sleep affect how you learn from reward or punishment? Reinforcement learning after 2 nights of sleep restriction.

To learn from feedback (trial and error) is essential for all species. Insufficient sleep has been found to reduce the sensitivity to feedback as well as increase reward sensitivity. To determine whether insufficient sleep alters learning from positive and negative feedback, healthy participants (n = 32, mean age 29.0 years, 18 women) were tested once after normal sleep (8 hr time in bed for 2 nights) and once after 2 nights of sleep restriction (4 hr/night) on a probabilistic selection task where learning behaviour was evaluated in three ways: as generalised learning, short-term win-stay/lose-shift learning strategies, and trial-by-trial learning rate. Sleep restriction did not alter the sensitivity to either positive or negative feedback on generalised learning. Also, short-term win-stay/lose-shift strategies were not affected by sleep restriction. Similarly, results from computational models that assess the trial-by-trial update of stimuli value demonstrated no difference between sleep conditions after the first block. However, a slower learning rate from negative feedback when evaluating all learning blocks was found after sleep restriction. Despite a marked increase in sleepiness and slowed learning rate for negative feedback, sleep restriction did not appear to alter strategies and generalisation of learning from positive or negative feedback.

GUESS: projecting machine learning scores to well-calibrated probability estimates for clinical decision-making.

MOTIVATION: Clinical decision support systems have been applied in numerous fields, ranging from cancer survival toward drug resistance prediction. Nevertheless, clinical decision support systems typically have a caveat: many of them are perceived as black-boxes by non-experts and, unfortunately, the obtained scores cannot usually be interpreted as class probability estimates. In probability-focused medical applications, it is not sufficient to perform well with regards to discrimination and, consequently, various calibration methods have been developed to enable probabilistic interpretation. The aims of this study were (i) to develop a tool for fast and comparative analysis of different calibration methods, (ii) to demonstrate their limitations for the use on clinical data and (iii) to introduce our novel method GUESS. RESULTS: We compared the performances of two different state-of-the-art calibration methods, namely histogram binning and Bayesian Binning in Quantiles, as well as our novel method GUESS on both, simulated and real-world datasets. GUESS demonstrated calibration performance comparable to the state-of-the-art methods and always retained accurate class discrimination. GUESS showed superior calibration performance in small datasets and therefore may be an optimal calibration method for typical clinical datasets. Moreover, we provide a framework (CalibratR) for R, which can be used to identify the most suitable calibration method for novel datasets in a timely and efficient manner. Using calibrated probability estimates instead of original classifier scores will contribute to the acceptance and dissemination of machine learning based classification models in cost-sensitive applications, such as clinical research. AVAILABILITY AND IMPLEMENTATION: GUESS as part of CalibratR can be downloaded at CRAN.

Short sleep-poor sleep? A polysomnographic study in a large population-based sample of women.

There is a lack of studies on the association between total sleep time (TST) and other polysomnographical parameters. A key question is whether a short sleep is an expression of habitual short sleep, or whether it reflects temporary impairment. The purpose of the present study was to investigate the association between TST and amount of sleep stages and sleep continuity measures, in a large population-based sample of women (n = 385), sleeping at home in a normal daily life setting. The results show that sleep efficiency, N1 (min), N2 (min), REM (min), REM% and proportion of long sleep segments, increased with increasing TST, whereas the number of awakenings/hr, the number of arousals/hr, N1% and REM intensity decreased. In addition, longer sleep was more associated with TST being perceived as of "usual" duration and with better subjective sleep quality. TST was not associated with habitual reported sleep duration. It was concluded that short TST of a recorded sleep in a real-life context may be an indicator of poor objective sleep quality for that particular sleep episode. Because individuals clearly perceived this reduction, it appears that self-reports of poor sleep quality often may be seen as indicators of poor sleep quality. It is also concluded that PSG-recorded sleep duration does not reflect habitual reported sleep duration in the present real-life context.

Effect of sleep deprivation on emotional working memory.

The emotional dysregulation and impaired working memory found after sleep loss can have severe implications for our daily functioning. Considering the intertwined relationship between emotion and cognition in stimuli processing, there could be further implications of sleep deprivation in high-complex emotional situations. Although studied separately, this interaction between emotion and cognitive processes has been neglected in sleep research. The aim of the present study was to investigate the effect of 1 night of sleep deprivation on emotional working memory. Sixty-one healthy participants (mean age: 23.4 years) were either sleep deprived for 1 night (n = 30) or had a normal night's sleep (n = 31). They performed an N-back task with two levels of working memory load (1-back and 3-back) using positive, neutral and negative picture scenes. Sleep deprivation, compared with full night sleep, impaired emotional working memory accuracy, but not reaction times. The sleep-deprived participants, but not the controls, responded faster to positive than to negative and neutral pictures. The effect of sleep deprivation was similar for both high and low working memory loads. The results showed that although detrimental in terms of accuracy, sleep deprivation did not impair working memory speed. In fact, our findings indicate that positive stimuli may facilitate working memory processing speed after sleep deprivation.

Mood impairment is stronger in young than in older adults after sleep deprivation.

Sleep deprivation commonly impairs affective regulation and causes worse mood. However, the majority of previous research concerns young adults. Because susceptibility to sleep deprivation and emotion regulation change distinctively across adult age, we tested here the hypothesis that the effect of sleep deprivation on mood is stronger in young than in older adults. In an experimental design, young (18-30 years) and older adults (60-72 years) participated in either a sleep control (young, n = 63; older, n = 47) or a total sleep deprivation condition (young, n = 61; older, n = 47). Sleepiness, mood and common symptoms of sleep deprivation were measured using established questionnaires and ratings. Sleep-deprived participants felt more sleepy, stressed and cold, and reported lower vigour and positive affect, regardless of age. All the other outcome measures (negative affect, depression, confusion, tension, anger, fatigue, total mood disturbance, hunger, cognitive attenuation, irritability) showed a weaker response to sleep deprivation in the older group, as indicated by age*sleep deprivation interactions (ps < 0.05). The results show that older adults are emotionally less affected by sleep deprivation than young adults. This tolerance was mainly related to an attenuated increase in negative mood. This could possibly be related to the well-known positivity effect, which suggests that older adults prioritize regulating their emotions to optimize well-being. The results also highlight that caution is warranted when generalizing results from sleep deprivation studies across the adult lifespan.

Influence of buffy coat-derived putative endothelial progenitor cells on tumor growth and neovascularization in oral squamous cell carcinoma xenografts.

OBJECTIVES: The aim of this murine in vivo study was to investigate whether buffy coat-derived putative endothelial progenitor cells (BCEPC) alter tumor growth and neovascularization in oral squamous cell carcinomas (OSCC). MATERIALS AND METHODS: A murine xenograft model using the PCI-13 oral cancer cell line was deployed of which n = 24 animals received 2 × 106 BCEPC by transfusion whereas the control group (n = 24) received NaCl (0.9%) instead. Tumor size, volume, and capillary density were determined by sonography and measurement with a caliper. Immunohistochemical analysis was carried out with antibodies specific for Cytokeratins, Flt-4, Podoplanin, and Vimentin. RESULTS: In the experimental group, systemic application of BCEPC significantly increased tumor volume to 362.49% (p = 0.0012) and weight to 352.38% (p = 0.0018) as well as vascular densities to 162.15% (p = 0.0021) compared with control tumors. In addition, BCEPC-treated xenografts exhibited higher Cytokeratin expression levels by a factor of 1.47 (p = 0.0417), Podoplanin by a factor of 3.3 (p = 0.0020) and Vimentin by a factor of 2.5 (p = 0.0001), respectively. CONCLUSIONS: Immunohistochemical investigations support the notion that BCEPC transfusion influences neovascularization and lymphatic vessel density, thereby possibly promoting tumor progression. Future studies, which will include gene expression analysis, should help to define the possible role of BCEPC during OSCC progression in more detail. CLINICAL RELEVANCE: Endothelial progenitor cells (EPCs) could serve as a target structure for the treatment of OSCC and possibly other solid tumors.

Effects of late-night short-sleep on in-home polysomnography: relation to adult age and sex.

Bedtime is frequently delayed by many factors in life, and a homeostatic response to the delay may compensate partly for increased time awake and shortened sleep. Because sleep becomes shorter with age and women complain of disturbed sleep more often than men, age and sex differences in the homeostatic response to a delayed bedtime may modify the homeostatic response. The purpose of the present study was to investigate the effect of late-night short-sleep (3 h with awakening at about 07:00 hours) on in-home recorded sleep in men and women in two age groups (20-30 and 65-75 years). Results (N = 59) showed that late-night short-sleep was associated with an increase in percentage of N3 sleep and a decrease in percentage of rapid eye movement sleep, as well as decreases in several measures of sleep discontinuity and rapid eye movement density. Men showed a smaller decrease in percentage of rapid eye movement sleep than women in response to late-night short-sleep, as did older individuals of both sexes compared with younger. Older men showed a weaker percentage of N3 sleep in response to late-night short-sleep than younger men. In general, men showed a greater percentage of rapid eye movement sleep and a lower percentage of N3 sleep than women, and older individuals showed a lower percentage of N3 sleep than younger. In particular, older men showed very low levels of percentage of N3 sleep. We conclude that older males show less of a homeostatic response to late-night short-sleep. This may be an indication of impaired capacity for recovery in older men. Future studies should investigate if this pattern can be linked to gender-associated differences in morbidity and mortality.

Age affects sleep microstructure more than sleep macrostructure.

It is well known that the quantity and quality of physiological sleep changes across age. However, so far the effect of age on sleep microstructure has been mostly addressed in small samples. The current study examines the effect of age on several measures of sleep macro- and microstructure in 211 women (22-71 years old) of the 'Sleep and Health in Women' study for whom ambulatory polysomnography was registered. Older age was associated with significantly lower fast spindle (effect size f2  = 0.32) and K-complex density (f2  = 0.19) during N2 sleep, as well as slow-wave activity (log) in N3 sleep (f2  = 0.21). Moreover, total sleep time (f2  = 0.10), N3 sleep (min) (f2  = 0.10), rapid eye movement sleep (min) (f2  = 0.11) and sigma (log) (f2  = 0.05) and slow-wave activity (log) during non-rapid eye movement sleep (f2  = 0.09) were reduced, and N1 sleep (f2  = 0.03) was increased in older age. No significant effects of age were observed on slow spindle density, rapid eye movement density and beta power (log) during non-rapid eye movement sleep. In conclusion, effect sizes indicate that traditional sleep stage scoring may underestimate age-related changes in sleep.

The relation between polysomnography and subjective sleep and its dependence on age - poor sleep may become good sleep.

Women complain more about sleep than men, but polysomnography (PSG) seems to suggest worse sleep in men. This raises the question of how women (or men) perceive objective (PSG) sleep. The present study sought to investigate the relation between morning subjective sleep quality and PSG variables in older and younger women. A representative sample of 251 women was analysed in age groups above and below 51.5 years (median). PSG was recorded at home during one night. Perceived poor sleep was related to short total sleep time (TST), long wake within total sleep time (WTSP), low sleep efficiency and a high number of awakenings. The older women showed lower TST and sleep efficiency and higher WTSP for a rating of good sleep than did the younger women. For these PSG variables the values for good sleep in the older group were similar to the values for poor sleep in the young group. It was concluded that women perceive different levels of sleep duration, sleep efficiency and wake after sleep onset relatively well, but that older women adjust their objective criteria for good sleep downwards. It was also concluded that age is an important factor in the relation between subjective and objective sleep.

The effect of partial sleep deprivation on computer-based measures of fitness to drive.

PURPOSE: Using a partial sleep deprivation paradigm, the aim of the study was to investigate the sensitivity of a computer-based test battery of fitness to drive to detect impairments related to sleepiness. METHODS: Forty-seven healthy subjects (34 females, mean age 26.0 ± 6.8 years) participated in a counterbalanced within-subject design of two conditions: (i) normal night sleep and (ii) partial sleep deprivation (PSD) with 4 h time in bed. For the assessment of fitness to drive, we used a validated traffic psychological test battery. Moreover, well-established measures of sleepiness highly responsive to sleep deprivation were applied: the Karolinska Sleepiness Scale (KSS), pupillography (Pupil Unrest Index (PUI) as physiological sleepiness indicator) and two sustained attention tasks (psychomotor Vigilance Task and Mackworth Clock Test). RESULTS: Subjective and physiological sleepiness were significantly increased after PSD, accompanied by large (d > 1.50 for KSS) and medium (d = 0.55 for PUI) effect sizes. Sleepiness-related performance decrements were found in both sustained attention tasks (d = 0.59-0.77). Assessing driving-related ability, PSD induced decrements only in the test domain Reaction Test (reaction time d = 0.54 and motor time d = 0.45). All other subtests-as well as the overall judgement of fitness to drive-were not significantly affected by PSD. CONCLUSION: In contrast to established tests of sustained attention and subjective sleepiness, computer-based test batteries of fitness to drive might lack sensitivity to core aspects of sleepiness as they mainly consist of short and stimulating subtests. Therefore, tasks that require sustained attention should be an essential part of traffic psychological test batteries when sleepiness is a potential issue.

Having to stop driving at night because of dangerous sleepiness--awareness, physiology and behaviour.

A large number of accidents are due to the driver falling asleep at the wheel, but details of this link have not been studied on a real road. The purpose of the present study was to describe the development of sleepiness indicators, leading to the drive being terminated prematurely by the onboard expert driving instructor because of imminent danger. Eighteen individuals participated during a day drive and a night drive on a motorway (both 90 min). Eight drivers terminated (N) prematurely (after 43 min) because of sleep-related imminent danger [according to the driving instructor or their own judgement (two cases)]. The results showed very high sleepiness ratings (8.5 units on the Karolinska Sleepiness Scale) immediately before termination (<7 at a similar time interval for those 10 who completed the drive). Group N also showed significantly higher levels of sleep intrusions on the electroencephalography/electro-oculography (EEG/EOG) than those who completed the drive (group C). The sleep intrusions were increased in group N during the first 40 min of the night drive. During the day drive, sleep intrusions were increased significantly in group N. The night drive showed significant increases of all sleepiness indicators compared to the day drive, but also reduced speed and driving to the left in the lane. It was concluded that 44% of drivers during late-night driving became dangerously sleepy, and that this group showed higher perceived sleepiness and more sleep intrusions in the EEG/EOG.

What do women mean by poor sleep? A large population-based sample with polysomnographical indicators, inflammation, fatigue, depression, and anxiety.

Survey studies indicate that reports of disturbed sleep are prevalent and may be prospectively linked to several major diseases. However, it is not clear what self-reported disturbed sleep represents, since the link with objective sleep measures (polysomnography; PSG) seems very weak. The purpose of the present study was to try to investigate what combination of variables (PSG, inflammation, fatigue, anxiety, depression) that would characterize those who complain of disturbed sleep. This has never been done before. Participants were 319 women in a population-based sample, who gave ratings of sleep quality, fatigue, depression, and anxiety, then had their sleep recorded at home, and had blood drawn the following morning for analysis of immune parameters. Correlations and hierarchical multivariable regression analyses were applied to the data. For ratings of difficulties initiating sleep, the associations in the final step were ß = .22, (p < .001) for fatigue, ß = 0.22 (p < .001) for anxiety, and ß = 0.17 (p < .01) for sleep latency, with R2 = 0.14. The rating of repeated awakenings was associated with fatigue (ß = 0.35, p < .001) and C-reactive protein (CRP) (ß = 0.12, p < .05), with R2 = 0.19. The rating of early morning awakenings was associated with fatigue (ß = 0.31, p < .001), total sleep time (TST) (ß = -0.20, p < .01), and CRP (ß = 0.15, p < .05), with R2 = 0.17. Interleukin-6 and Tumour Necrosis Factor were not associated with ratings of sleep problems. The results indicate that subjective fatigue, rather than objective sleep variables, is central in the perception of poor sleep, together with CRP.

Sleep in everyday life - relationship to mood and performance in young and older adults: a study protocol.

Laboratory based sleep deprivation studies demonstrate that lack of sleep impairs well-being and performance ability, but suggest that these effects are mitigated in older adults. Yet, much less is known whether day-to-day variations of sleep have similar consequences in the context of everyday life. This project uses an intensive longitudinal design to investigate the occurrence of day-to-day variations in sleep and their impact on mood and performance in everyday life and to examine whether effects differ between young and older adults. We aim to include 160 young (18-30 years) and 160 older adults (55-75 years) to complete a 21-day experience sampling method (ESM) protocol. During the ESM period, participants are asked to fill in (i) a brief morning questionnaire, (ii) 8 short daytime questionnaires addressing momentary well-being, sleepiness, stress, and mind wandering, followed by a 1 min cognitive task and (iii) a brief evening questionnaire, all delivered via a mobile phone application. Sleep will be measured using self-reports (daily questions) and objectively with wrist actigraphy. The impact of adult age on mean levels and intraindividual variability of sleep will be analyzed using mixed-effects location scale models. The impact of sleep on daily cognitive performance will be analyzed using multilevel linear mixed models. The relationship of sleep to mean values and variability of positive and negative affect in young and older adults will be analyzed using mixed-effects location scale modeling. The overarching purpose of the project is improving the current knowledge on the occurrence of day-to-day variations in sleep and their relationship to performance as well as positive and negative affect in young and older adults.

The Polysomnographical Meaning of Changed Sleep Quality-A Study of Treatment with Reduced Time in Bed.

BACKGROUND: Reports of poor sleep are widespread, but their link with objective sleep (polysomnography-PSG) is weak in cross-sectional studies. In contrast, the purpose of this study was to investigate the association between changes in subjective and objective sleep variables using data from a study of the reduction in time in bed (TIB). METHODS: One sleep recording was carried out at baseline and one at treatment week 5 (end of treatment) (N = 34). RESULTS: The Karolinska Sleep Quality Index improved and was correlated with improvement in sleep efficiency (r = 0.41, p < 0.05) and reduction in TIB (r = -0.47, p < 0.01) and sleep latency (r = 0.36, p < 0.05). The restorative sleep index showed similar results. Improvements in the insomnia severity index (ISI) essentially lacked correlations with changes in the PSG variables. It was suggested that the latter may be due to the ISI representing a week of subjective sleep experience, of which a single PSG night may not be representative. CONCLUSIONS: It was concluded that changes in the subjective ratings of sleep are relatively well associated with changes in the PSG-based sleep continuity variables when both describe the same sleep.

In-car countermeasures open window and music revisited on the real road: popular but hardly effective against driver sleepiness.

This study investigated the effects of two very commonly used countermeasures against driver sleepiness, opening the window and listening to music, on subjective and physiological sleepiness measures during real road driving. In total, 24 individuals participated in the study. Sixteen participants received intermittent 10-min intervals of: (i) open window (2 cm opened); and (ii) listening to music, during both day and night driving on an open motorway. Both subjective sleepiness and physiological sleepiness (blink duration) was estimated to be significantly reduced when subjects listened to music, but the effect was only minor compared with the pronounced effects of night driving and driving duration. Open window had no attenuating effect on either sleepiness measure. No significant long-term effects beyond the actual countermeasure application intervals occurred, as shown by comparison to the control group (n = 8). Thus, despite their popularity, opening the window and listening to music cannot be recommended as sole countermeasures against driver sleepiness.

Total sleep time, sleep efficiency, and next day subjective sleepiness in a large group of women.

The relationship between sleep duration and sleepiness has seen much research, but no data are available on the association between polysomnographically (PSG) determined total sleep time (TST) (or other PSG variables) and subjective sleepiness during the subsequent day in individuals in their habitual life situation. The purpose of the present study was to study the association between TST and sleep efficiency (SE) (and other PSG variables) and next-day sleepiness at 7 times of the day. A large population-based group of women (N = 400) participated. Daytime sleepiness was measured with the Karolinska Sleepiness Scale (KSS). The association was studied through analysis of variance (ANOVA), as well as regression analyses. For SE there was a significant difference in sleepiness across groups with >90%, 80%-89.99%, and <80% SE (F = 7.2, p < .001, eta2 = 0.04), with lowest sleepiness in the first group. In contrast, TST groups of <6 h, 6-6.99 h, and ≥7 h did not differ significantly. In addition, a pronounced U-shape (eta2 > 0.45) was seen for both analyses, with maximum sleepiness at bedtime (≈ 7.5 KSS units). A multiple regression analysis, including all PSG variables (adjusted for age and BMI), showed that SE was a significant predictor (ß = 0.16, p < .05) of mean sleepiness, even after depression, anxiety, and subjective sleep duration were entered, but this was eliminated by subjective sleep quality. It was concluded that high SE is modestly associated with lower next-day sleepiness in women in a real-life context, but that TST is not.

We Have a Lot to Do: Lack of Sexual Protection and Information-Results of the German-Language Online Survey "Let's Talk About Chemsex".

Background: The prevalence of chemsex and sexualized substance use is increasing in several European countries, particularly among men who have sex with men. In this subgroup, illegal substance use is associated with increased sexual risk behavior, which can result in severe physical and psychological impairments. The present study examined the incidence and prevalence of chemsex in German-speaking countries. Methods: To further describe the high-risk group of Chemsex users, participants (N = 429) were asked about their psychotropic substance use, sexual and health-related behavior, health status, and socio-demographic information by using an online questionnaire. Whether Chemsex has negative effects on well-being was measured with the WHO well-being index. Of additional interest was how informed Chemsex users are about the topic and what needs are placed on the practitioners. The online questionnaire consisted of 105 items, and data was collected from March to May 2019. Thousand forty seven datasets were saved with a dropout rate of 59%, 123 completed questionnaires fulfilled the criteria for chemsex users (n =123). Results: There were no significant differences in well-being between chemsex users and non-users. All participants protected themselves against sexually transmitted diseases irregularly or not at all. The majority of chemsex users reported intermittently using illegal substances (ketamine, methamphetamine, mephedrone, γ-butyrolactone/γ-hydroxy butyric acid). They viewed their sexual and substance use behavior as problematic, but few showed motivation for behavior change. Chemsex users clearly expressed a need for more information and advice centers. Conclusion: The results provide information on chemsex users that can be used for the future development of a therapy manual and thus contribute to improving health care for this group. The prevalence of chemsex is increasing and urgently needs more research to protect clients from health impairments and stigmatization.

A combined fMRI and EMG study of emotional contagion following partial sleep deprivation in young and older humans.

Sleep deprivation is proposed to inhibit top-down-control in emotion processing, but it is unclear whether sleep deprivation affects emotional mimicry and contagion. Here, we aimed to investigate effects of partial sleep deprivation on emotional contagion and mimicry in young and older humans. Participants underwent partial sleep deprivation (3 h sleep opportunity at the end of night), crossed-over with a full sleep condition in a balanced order, followed by a functional magnetic resonance imaging and electromyography (EMG) experiment with viewing of emotional and neutral faces and ratings of emotional responses. The final sample for main analyses was n = 69 (n = 36 aged 20-30 years, n = 33 aged 65-75 years). Partial sleep deprivation caused decreased activation in fusiform gyri for angry faces and decreased ratings of happiness for all stimuli, but no significant effect on the amygdala. Older participants reported more anger compared to younger participants, but no age differences were seen in brain responses to emotional faces or sensitivity to partial sleep deprivation. No effect of the sleep manipulation was seen on EMG. In conclusion, emotional contagion, but not mimicry, was affected by sleep deprivation. Our results are consistent with the previously reported increased negativity bias after insufficient sleep.The Stockholm sleepy brain study: effects of sleep deprivation on cognitive and emotional processing in young and old. https://clinicaltrials.gov/ct2/show/NCT02000076 .

Gray Matter Volume Correlates of Sleepiness: A Voxel-Based Morphometry Study in Younger and Older Adults.

BACKGROUND: Subjectively experienced sleepiness is a problem in society, possibly linked with gray matter (GM) volume. Given a different sleep pattern, aging may affect such associations, possibly due to shrinking brain volume. PURPOSE: The purpose of the present study was to investigate the association between subjectively rated sleepiness and GM volume in thalamus, insula, hippocampus, and orbitofrontal cortex of young and older adults, after a normal night's sleep. METHODS: Eighty-four healthy individuals participated (46 aged 20-30 years, and 38 aged 65-75 years). Morphological brain data were collected in a 3T magnetic resonance imaging (MRI) scanner. Sleepiness was rated multiple times during the imaging sessions. RESULTS: In older, relative to younger, adults, clusters within bilateral mid-anterior insular cortex and right thalamus were negatively associated with sleepiness. Adjustment for the immediately preceding total sleep time eliminated the significant associations. CONCLUSION: Self-rated momentary sleepiness in a monotonous situation appears to be negatively associated with GM volume in clusters within both thalamus and insula in older individuals, and total sleep time seems to play a role in this association. Possibly, this suggests that larger GM volume in these clusters may be protective against sleepiness in older individuals. This notion needs confirmation in further studies.