Psychometric Properties of the Sleep Locus of Control (SLOC) Scale in a Portuguese Sample.

Over the past few decades, research has suggested that cognitive variables play a key role in sleep disorders, particularly, in insomnia. The SLOC (Sleep Locus of Control Scale) evaluates the sleep locus of control, which is associated with the degree to which an individual attributes her/his experiences of sleep to chance or internal causes. The aim of this study was to develop the first translation and adaptation of the SLOC into the European Portuguese, as well as to analyze its psychometric properties. In this study, it was recruited a sample of 2029 Portuguese Higher Education students, aged ≥ 18 years, where approximately 75% of the sample were women and 25% men. The results showed that the SLOC had acceptable internal consistency value (α = .64), considering that it is a measure with a reduced number of items. As in the original study, a principal component analysis with varimax rotation identified two components. A parallel analysis was also conducted, identifying two factors. The correlation between the two subscales "internal sleep locus of control" and "chance sleep locus of control" was positive albeit of low magnitude (r = .15). Through the analysis carried out, it was also observed that individuals with "insomnia", relative to those without, had a more chance sleep locus of control. Overall, these findings show similarities with the original study. The SLOC seems to be a useful psychological assessment measure to be used in clinical and research settings.

Mapping genomic loci implicates genes and synaptic biology in schizophrenia.

Schizophrenia has a heritability of 60-80%1, much of which is attributable to common risk alleles. Here, in a two-stage genome-wide association study of up to 76,755 individuals with schizophrenia and 243,649 control individuals, we report common variant associations at 287 distinct genomic loci. Associations were concentrated in genes that are expressed in excitatory and inhibitory neurons of the central nervous system, but not in other tissues or cell types. Using fine-mapping and functional genomic data, we identify 120 genes (106 protein-coding) that are likely to underpin associations at some of these loci, including 16 genes with credible causal non-synonymous or untranslated region variation. We also implicate fundamental processes related to neuronal function, including synaptic organization, differentiation and transmission. Fine-mapped candidates were enriched for genes associated with rare disruptive coding variants in people with schizophrenia, including the glutamate receptor subunit GRIN2A and transcription factor SP4, and were also enriched for genes implicated by such variants in neurodevelopmental disorders. We identify biological processes relevant to schizophrenia pathophysiology; show convergence of common and rare variant associations in schizophrenia and neurodevelopmental disorders; and provide a resource of prioritized genes and variants to advance mechanistic studies.

Contributions of common genetic variants to risk of schizophrenia among individuals of African and Latino ancestry.

Schizophrenia is a common, chronic and debilitating neuropsychiatric syndrome affecting tens of millions of individuals worldwide. While rare genetic variants play a role in the etiology of schizophrenia, most of the currently explained liability is within common variation, suggesting that variation predating the human diaspora out of Africa harbors a large fraction of the common variant attributable heritability. However, common variant association studies in schizophrenia have concentrated mainly on cohorts of European descent. We describe genome-wide association studies of 6152 cases and 3918 controls of admixed African ancestry, and of 1234 cases and 3090 controls of Latino ancestry, representing the largest such study in these populations to date. Combining results from the samples with African ancestry with summary statistics from the Psychiatric Genomics Consortium (PGC) study of schizophrenia yielded seven newly genome-wide significant loci, and we identified an additional eight loci by incorporating the results from samples with Latino ancestry. Leveraging population differences in patterns of linkage disequilibrium, we achieve improved fine-mapping resolution at 22 previously reported and 4 newly significant loci. Polygenic risk score profiling revealed improved prediction based on trans-ancestry meta-analysis results for admixed African (Nagelkerke's R2 = 0.032; liability R2 = 0.017; P < 10-52), Latino (Nagelkerke's R2 = 0.089; liability R2 = 0.021; P < 10-58), and European individuals (Nagelkerke's R2 = 0.089; liability R2 = 0.037; P < 10-113), further highlighting the advantages of incorporating data from diverse human populations.

Profiles of Subjective Daytime Sleepiness through Cluster Analysis.

Sleepiness propensity and sleepiness perception are two relevant dimensions of the general multidimensional sleepiness construct. In the current study, the aim was to identify eventual homogeneous subgroups when sleepiness propensity and sleepiness perception measures are combined. Data from 678 undergraduate students (aged 17 to 24 years) from a medical school were analyzed. A Two-Step Cluster Analysis was performed taken into consideration sleepiness propensity and sleepiness perception measures as clustering variables. Four different clusters were identified. Additionally, the two groups comprising higher levels of sleepiness perception (i.e., "high perception, low propensity" and "high subjective daytime sleepiness" clusters) had the most compromised results in some of the sleep-related variables examined - sleep needs, sleep latency, sleep quality, sleep sufficiency, self-reported insomnia, sleep reactivity to stress, and cognitive arousal - and in some of non-sleep related variables, such as neuroticism and affect. As to non-sleep variables, those groups reported higher scores in neuroticism, arousability, self-reported mental health and affective states. The identification of distinct groups concerning self-reported sleepiness may bring new avenues for research and understanding of the specific and differential role of sleepiness and its dimensions in sleep health and sleep disturbances, in particular, insomnia disorder.

BaSIQS - basic scale on insomnia complaints and quality of sleep: reliability, norms, validity, and accuracy studies, based on clinical and community samples.

This research focused on the Basic Scale on Insomnia Symptoms and Quality of Sleep (BaSIQS), formerly validated in undergraduates using the Pittsburgh Sleep Quality Index (PSQI), and aimed to expand internal consistency analysis, examine thoroughly its validity, and determine its clinical accuracy. Considering objective and subjective measures, recruiting non-clinical and clinical samples, this research implemented a comprehensive approach to examine convergent and discriminant validity, confirmatory factor analyses, and the BaSIQS sensitivity and specificity. The BaSIQS was filled out along with the Insomnia Severity Index (ISI), questions on sleep-wake schedules, Composite Scale of Morningness (CSM) and Brief Symptom Inventory-18 (BSI-18) by 1198 adults, 18-64 years old, plus another 30 who wore actimeters, recruited in community settings. A clinical group of 30 chronic insomnia disorder patients also participated. Cronbach alpha coefficient was 0.80. A two-factor structure was confirmed. The association between BaSIQS and ISI was large, whereas actigraphy correlations were medium or small. Medium to non-significant correlations were found concerning conceptually different self-report measures. Comparing the clinic and control groups, the former showed poorer sleep, with a large effect size. Receiver operating characteristic analysis revealed an area under curve = 0.9, and an optimal cut-off score >15. In conclusion, results on reliability, validity, and accuracy provide support to the utility of the BaSIQS both in community and clinical settings, for research and practical purposes.

Pre-Sleep Arousal Scale (PSAS): psychometric study of a European Portuguese version.

OBJECTIVE/BACKGROUND: Pre-sleep arousal constitutes one of the major features of insomnia. As such, it is imperative to have adequate instruments to measure this construct in both clinical and research settings. The Pre-Sleep Arousal Scale (PSAS) is the most well-known measure to evaluate pre-sleep arousal. The current study aimed to examine some of the psychometric properties of a European Portuguese version of the scale. PARTICIPANTS/METHODS: For this purpose, data from 691 undergraduate students from a medical school were analyzed. Internal consistency indices and factor analysis were performed. In addition, the association between the PSAS and its subscales with other measures was also examined. Finally, PSAS scores of self-reported insomniacs were compared with those of self-reported non-insomniacs. RESULTS: The results indicated that the PSAS comprises a cognitive scale and a somatic scale, both with adequate internal consistency indices (α = 0.82 and 0.79, respectively). However, a three-factor solution also seemed plausible, suggesting that the original somatic arousal subscale might be divided into two subscales. Significant associations between the PSAS total score and its subscales were found with other concurrent measures such as sleep reactivity to stress, arousability and neuroticism. Self-defined insomniacs presented higher levels of cognitive and somatic arousal than healthy individuals. CONCLUSIONS: Further investigations of the PSAS are needed to refine its psychometric properties and explore its research and clinical utility in other populations.

Portuguese Version of the Arousal Predisposition Scale: Preliminary Evidence for a Two-Factor Structure in a Nonclinical Sample.

It is known that there is significant variability in arousal levels of the individuals. The Arousal Predisposition Scale (APS) is a questionnaire intended to measure individual differences in arousability. In the current work, our aim was to present the initial psychometric properties of the Portuguese version of the APS. Three hundred forty-five undergraduate medical students from both genders were enrolled. All participants filled out a set of questionnaires-which contained the APS-at the end of their lectures and out of the evaluation period. The APS showed good internal consistency (α = .85) and discriminated individuals with extreme scores. Further, in general, the scale discriminated as well both genders pertaining to the individual items and total score. In terms of scale structure, two related factors were extracted (F1 = emotional reactivity and F2 = trait anxiety). Significant associations among APS and other sleep and psychological self-report variables were also observed. The APS seems to be a reliable and valid instrument to assess self-reported physiological arousability, at least in a sample of young adults. The two-factor composition will require more studies to be replicated in similar groups and, particularly, in clinical samples.

Assessing Stress-Induced Sleep Reactivity in College Students: The European Portuguese Version of the Ford Insomnia Response to Stress Test (FIRST).

OBJECTIVE AND BACKGROUND: Over the past few years, the comprehensive models of insomnia have exhibited impressive developments. However, there is scarce knowledge on predisposing or vulnerability factors for insomnia. One of the most promising constructs to aid in filling this gap is stress-induced sleep reactivity assessed through self-report. Our aim was to study the psychometric properties of the European Portuguese version of the Ford Insomnia Response to Stress Test (FIRST). PARTICIPANTS: We recruited a large sample of students attending medical school (N = 699). METHODS: Several analyses were carried out such as internal consistency, construct validity, and discriminant groups' analysis. RESULTS: It was observed that FIRST-PT shows good internal consistency (Cronbach´s alpha = .81) and validity indicators. Interestingly, and contrary to what was observed in the previously published studies on psychometric properties of the FIRST, it was observed that a two-factor solution (Factor I = rumination, Factor II = worry) was the most adequate one to explain the correlation matrix, accounting for approximately 44% of the total variance. CONCLUSIONS: The FIRST-PT proved to be a useful and reliable tool to measure stress-induced sleep reactivity. However, these results should be replicated in other groups, particularly clinical samples, in order to verify the stability of its factorial dimension.

Circadian preferences in young adults: Psychometric properties and factor structure of the Portuguese version of the Preferences Scale (PS-6).

Morningness is a trait-like variable which has been extensively studied within chronobiology. Despite the number of existing measures to assess morningness, there is a need for brief instruments that are psychometrically sound to be used in applied settings. Accordingly, the modified version of the Preferences Scale (PS-6) comprises six items and was reported to have adequate reliability and satisfactory validity indicators. In this article, the psychometric properties of the Portuguese version of the PS-6 are reported. A total of 700 students attending medical school were recruited, and this sample was randomly divided into two groups. In the first group (n = 352), we assessed the internal consistency calculations and conducted a principal component analysis of the posited structure. In the second group (n = 348), we conducted a confirmatory factor analysis (CFA) using structural equation modeling. Overall, the results indicated that the PS-6 has adequate reliability (α = .75) and is constituted by two components: (I) preferred cognitive activities timings and (II) preferred sleeping-eating timings, respectively. In conclusion, the Portuguese version of the PS seems suitable for use in research and applied settings such as shift work schedules management. However, the applicability of the PS-6 in other samples and further validity indicators should be both investigated. The use of actigraphy and biological measures should also be collected to enhance the robustness of the PS-6.

Basic Scale on Insomnia complaints and Quality of Sleep (BaSIQS): reliability, initial validity and normative scores in higher education students.

Based on successive samples totaling more than 5000 higher education students, we scrutinized the reliability, structure, initial validity and normative scores of a brief self-report seven-item scale to screen for the continuum of nighttime insomnia complaints/perceived sleep quality, used by our team for more than a decade, henceforth labeled the Basic Scale on Insomnia complaints and Quality of Sleep (BaSIQS). In study/sample 1 (n = 1654), the items were developed based on part of a larger survey on higher education sleep-wake patterns. The test-retest study was conducted in an independent small group (n = 33) with a 2-8 week gap. In study/sample 2 (n = 360), focused mainly on validity, the BaSIQS was completed together with the Pittsburgh Sleep Quality Index (PSQI). In study 3, a large recent sample of students from universities all over the country (n = 2995) answered the BaSIQS items, based on which normative scores were determined, and an additional question on perceived sleep problems in order to further analyze the scale's validity. Regarding reliability, Cronbach alpha coefficients were systematically higher than 0.7, and the test-retest correlation coefficient was greater than 0.8. Structure analyses revealed consistently satisfactory two-factor and single-factor solutions. Concerning validity analyses, BaSIQS scores were significantly correlated with PSQI component scores and overall score (r = 0.652 corresponding to a large association); mean scores were significantly higher in those students classifying themselves as having sleep problems (p < 0.0001, d = 0.99 corresponding to a large effect size). In conclusion, the BaSIQS is very easy to administer, and appears to be a reliable and valid scale in higher education students. It might be a convenient short tool in research and applied settings to rapidly assess sleep quality or screen for insomnia complaints, and it may be easily used in other populations with minor adaptations.

Sleep-wake patterns reported by parents in hyperactive children diagnosed according to ICD-10, as compared to paired controls.

This study aimed primarily to compare the parent-reported sleep of children with ICD-10 hyperkinetic disorder (HKD) versus community children. Thirty children aged 5-13 years (83.3% boys) diagnosed with HKD by their child and adolescent psychiatrists took part in this study, plus 30 community children, matched for sex, age, and school year. Compared to the controls, the HKD children showed significantly later bedtimes, stronger bedtime resistance, longer sleep latency, shorter sleep; more frequent behaviors and symptoms concerning falling asleep into parents bed, needing something special to initiate sleep, nightmares, sleep talking, sleep bruxism, fear from darkness, bedwetting, and, most notably, loud snoring (26.7%); they also tended to show higher daytime somnolence. Attention deficit/hyperactivity disorder (ADHD)/HKD children may thus have more sleep-related problems than typically developing children. Alternatively, our results may reflect misdiagnoses; thus, special attention should be directed to comorbidity and differential diagnosis issues between sleep disturbances and ADHD/HKD.

Is positive affect in pregnancy protective of postpartum depression?

OBJECTIVE: To investigate the predictive/protective role of negative affect/positive affect in late pregnancy on the outcome of postpartum depression. METHODS: A total of 491 pregnant women participated in the study. The participants were asked to fill out a series of questionnaires, which included the Profile of Mood States, the Beck Depression Inventory-II, psychosocial variables and socio-demographic characteristics and were asked to participate in a psychiatric interview. After delivery, 272 mothers participated again in the study and filled out a similar series of questionnaires. RESULTS: Negative affect was associated with more intense depressive symptomatology, more self-perceived stress, lower self-reported social support, lower quality of life and perception of having a more difficult infant. By contrast, positive affect was negatively associated with these variables. Negative affect in late pregnancy increased the likelihood of experiencing postpartum depression (DSM-IV/OR = 2.1, 95%CI = 1.3-3.4, p = .003; ICD-10/OR = 2.1, 95%CI = 1.5-3.0, p < .001), while positive affect increased the odds of not having this condition (DSM-IV/OR = 2.0, 95%CI = 1.5-2.7, p = .042). CONCLUSION: In pregnancy, negative affect was a predictor of postpartum depression, whereas positive affect showed a protective role. Future studies are required to explore whether psychotherapeutic strategies focusing on decreasing negative affect and enhancing positive affect in the last trimester of pregnancy can reduce the risk of postpartum depression.

Is positive affect in pregnancy protective of postpartum depression?

OBJECTIVE: To investigate the predictive/protective role of negative affect/positive affect in late pregnancy on the outcome of postpartum depression. METHODS: A total of 491 pregnant women participated in the study. The participants were asked to fill out a series of questionnaires, which included the Profile of Mood States, the Beck Depression Inventory-II, psychosocial variables and socio-demographic characteristics and were asked to participate in a psychiatric interview. After delivery, 272 mothers participated again in the study and filled out a similar series of questionnaires. RESULTS: Negative affect was associated with more intense depressive symptomatology, more self-perceived stress, lower self-reported social support, lower quality of life and perception of having a more difficult infant. By contrast, positive affect was negatively associated with these variables. Negative affect in late pregnancy increased the likelihood of experiencing postpartum depression (DSM-IV/OR = 2.1, 95%CI = 1.3-3.4, p = .003; ICD-10/OR = 2.1, 95%CI = 1.5-3.0, p < .001), while positive affect increased the odds of not having this condition (DSM-IV/OR = 2.0, 95%CI = 1.5-2.7, p = .042). CONCLUSION: In pregnancy, negative affect was a predictor of postpartum depression, whereas positive affect showed a protective role. Future studies are required to explore whether psychotherapeutic strategies focusing on decreasing negative affect and enhancing positive affect in the last trimester of pregnancy can reduce the risk of postpartum depression.

Short forms of the postpartum depression screening scale: as accurate as the original form.

The aims of the present study were to develop three shorter forms of the Portuguese version of the Postpartum Depression Screening Scale (PDSS) as adapted and translated in Portugal, to analyse their psychometrics and to determine their cut-off points and associated conditional probabilities to screen for perinatal depression according to DSM-IV and ICD-10 criteria. In this study, 441 women in the third trimester of pregnancy and 453 in the third month of postpartum were interviewed for diagnostic purposes according to the Portuguese versions of the Diagnostic Interview for Genetic Studies and the Operational Criteria Checklist for Psychotic Illness. DSM-IV and ICD-10 classifications of depression were our gold standards for caseness. Three different shorter forms of the original Portuguese version of the PDSS were developed on the basis of reliability and factorial analysis. PDSS short versions, composed of seven and 21 (postpartum)/24 (pregnancy) items, presented significant reliability and validity and showed satisfactory combinations of sensitivity and specificity (≅80 %). The short forms of the original Portuguese version of the PDSS are valid alternatives to the 35-item version, given their equally precise screening performances, more concise structures and ease of completion.

Frost Multidimensional Perfectionism Scale: the portuguese version / Frost Multidimensional Perfectionism Scale: versão portuguesa

BACKGROUND: The Frost Multidimensional Perfectionism Scale is one of the most world widely used measures of perfectionism. OBJECTIVE: To analyze the psychometric properties of the Portuguese version of the Frost Multidimensional Perfectionism Scale. METHODS: Two hundred and seventeen (178 females) students from two Portuguese Universities filled in the scale, and a subgroup (n = 166) completed a retest with a four weeks interval. RESULTS: The scale reliability was good (Cronbach alpha = .857). Corrected item-total correlations ranged from .019 to .548. The scale test-retest reliability suggested a good temporal stability with a test-retest correlation of .765. A principal component analysis with Varimax rotation was performed and based on the Scree plot, two robust factorial structures were found (four and six factors). The principal component analyses, using Monte Carlo PCA for parallel analyses confirmed the six factor solution. The concurrent validity with Hewitt and Flett MPS was high, as well as the discriminant validity of positive and negative affect (Profile of Mood Stats-POMS). DISCUSSION: The two factorial structures (of four and six dimensions) of the Portuguese version of Frost Multidimensional Perfectionism Scale replicate the results from different authors, with different samples and cultures. This suggests this scale is a robust instrument to assess perfectionism, in several clinical and research settings as well as in transcultural studies.

CONTEXTO: A Escala Multidimensional de Perfeccionismo de Frost (FMPS) é uma das escalas mais usadas em todo o mundo para avaliar o perfeccionismo. OBJETIVO: Analisar as características psicométricas da versão portuguesa da FMPS. MÉTODOS: A amostra foi constituída por 217 estudantes do ensino superior (178 mulheres). Um subgrupo (n = 166) completou o reteste após quatro semanas. RESULTADOS: A consistência interna da escala mostrou ser elevada (alfa de Cronbach = ,857). As correlações item-total corrigido variaram entre ,019 e ,548. Os resultados também sugeriram uma boa estabilidade temporal da escala, sendo a correlação teste-reteste de ,765. Foi realizada a análise das componentes principais com rotação Varimax e com base no Scree plot foram extraídas duas soluções fatoriais robustas (quatro e seis fatores). A análise paralela (Monte Carlo PCA) confirmou a solução de seis fatores. A validade concorrente com a escala MPS de Hewitt e Flett foi elevada, assim como a sua capacidade discriminante dos afetos positivos e negativos (Perfil de Estados de Humor - POMS). CONCLUSÃO: As duas estruturas fatoriais (quatro e seis fatores) encontradas na versão portuguesa da Escala Multidimensional de Perfeccionismo de Frost replicam os resultados obtidos por diferentes autores, em diferentes amostras e culturas. Esse fato sugere que essa escala é um instrumento robusto para a avaliação do perfeccionismo em vários contextos, clínicos e de investigação, bem como em estudos transculturais.

Revisiting thyroid hormones in schizophrenia.

Thyroid hormones are crucial during development and in the adult brain. Of interest, fluctuations in the levels of thyroid hormones at various times during development and throughout life can impact on psychiatric disease manifestation and response to treatment. Here we review research on thyroid function assessment in schizophrenia, relating interrelations between the pituitary-thyroid axis and major neurosignaling systems involved in schizophrenia's pathophysiology. These include the serotonergic, dopaminergic, glutamatergic, and GABAergic networks, as well as myelination and inflammatory processes. The available evidence supports that thyroid hormones deregulation is a common feature in schizophrenia and that the implications of thyroid hormones homeostasis in the fine-tuning of crucial brain networks warrants further research.

Portuguese validation of the children's eating attitudes test / Validação portuguesa do teste de atitudes alimentares para crianças

BACKGROUND: The Eating Attitudes Test (EAT) is the most widely used instrument for evaluating eating disorders in adults and adolescents in a variety of cultures and samples.OBJECTIVE: The aim of this study was to analyse the psychometric properties of the Portuguese version of the Children's Eating Attitudes Test (ChEAT).METHOD: Nine hundred and fifty-six Portuguese secondary students (565 girls and 391 boys) answered the ChEAT. The test-retest reliability was obtained with data from 206 participants from the total sample who re-answered the questionnaire after 4-6 weeks. Psychometric analyses were carried out for the total sample and separately for girls and boys.RESULTS: Internal consistency and test-retest reliability were satisfactory. Principal components factorial analysis yielded four factors in the total sample, accounting for 42.35% of the total variance. Factor structure was similar in the total sample and in both genders. Factors were labelled: F1 "Fear of Getting Fat", F2 "Restrictive and Purgative Behaviours", F3 "Food Preoccupation" and F4 "Social Pressure to Eat". The concurrent validity, explored using the Contour Drawing Figure Rating Scale (CDRS) was high.DISCUSSION: The Portuguese version of the ChEAT is a valid and useful instrument for the evaluation of abnormal eating attitudes and behaviours among Portuguese adolescents.

CONTEXTO: O Teste de Atitudes Alimentares é o instrumento mais utilizado para avaliar distúrbios alimentares em adultos e adolescentes em uma variedade de culturas e amostras.OBJETIVO: O objetivo deste estudo foi avaliar as propriedades psicométricas da versão portuguesa da Escala de Atitudes Alimentares para Crianças (ChEAT).MÉ;TODO: Novecentos e cinquenta e seis alunos do ensino secundário (565 moças e 391 moços) responderam ao ChEAT. O cálculo da fidelidade teste-reteste foi feito por meio das respostas de 206 participantes da amostra total que voltaram a responder ao questionário após quatro a seis semanas. As análises psicométricas foram realizadas para o total da amostra e para ambos os sexos separadamente.RESULTADOS: A consistência interna e a fidelidade teste-reteste foram satisfatórias. A análise fatorial em componentes na amostra total resultou em quatro fatores que explicam 42,35% da variância total. A composição dos fatores foi semelhante na amostra total e em ambos os sexos. Os fatores denominaram-se: F1 "Medo de Engordar"; F2 "Comportamentos Restritivos e Purgativos"; F3 "Preocupação com a Comida" e F4 "Pressão Social para Comer". A validade concorrente foi explorada com a Escala de Silhuetas Corporais (CDFRS) e foi elevada.CONCLUSÃO: A versão portuguesa do ChEAT é um instrumento útil e válido para a avaliação de atitudes e comportamentos alimentares em adolescentes portugueses.

Sleep and academic performance in undergraduates: a multi-measure, multi-predictor approach.

The present study examined the associations of sleep patterns with multiple measures of academic achievement of undergraduate university students and tested whether sleep variables emerged as significant predictors of subsequent academic performance when other potential predictors, such as class attendance, time devoted to study, and substance use are considered. A sample of 1654 (55% female) full-time undergraduates 17 to 25 yrs of age responded to a self-response questionnaire on sleep, academics, lifestyle, and well-being that was administered at the middle of the semester. In addition to self-reported measures of academic performance, a final grade for each student was collected at the end of the semester. Univariate analyses found that sleep phase, morningness/eveningness preference, sleep deprivation, sleep quality, and sleep irregularity were significantly associated with at least two academic performance measures. Among 15 potential predictors, stepwise multiple regression analysis identified 5 significant predictors of end-of-semester marks: previous academic achievement, class attendance, sufficient sleep, night outings, and sleep quality (R(2)=0.14 and adjusted R(2)=0.14, F(5, 1234)= 40.99, p < .0001). Associations between academic achievement and the remaining sleep variables as well as the academic, well-being, and lifestyle variables lost significance in stepwise regression. Together with class attendance, night outings, and previous academic achievement, self-reported sleep quality and self-reported frequency of sufficient sleep were among the main predictors of academic performance, adding an independent and significant contribution, regardless of academic variables and lifestyles of the students.