Lorenzo Tonetti

Sex Difference in Sleep‐Time Preference and Sleep Need: A Cross‐Sectional Survey among Italian Pre‐Adolescents, Adolescents, and Adults

The aim of this study was to examine sex differences in sleep‐time preference by age among Italian pre‐adolescents, adolescents, and adults. The final sample consisted of 8,972 participants (5,367 females and 3,605 males) from 10 to 87 yrs of age. To assess preferred sleep habits, we considered the answers to the open‐ended questions of the Morningness‐Eveningness Questionnaire (MEQ). In agreement with previous studies, we found that sleep‐time preference started to shift toward eveningness from the age of 13 yrs. Females reached their peak in eveningness earlier (about 17 yrs of age) than males (about 21 yrs of age). Thereafter, the ideal sleep‐time preference advanced in men and women with increasing age. Females presented a more significant advanced sleep phase than males only during the years when sexual hormones are typically active. Moreover, females reported a longer ideal sleep duration than males across all age groups examined, except in over 55 yrs one. (Author correspondence: vincenzo.natale@unibo.it)

Relationship between Circadian Typology and Big Five Personality Domains

We explored the relationship between personality, based on the five‐factor model, and circadian preference. To this end, 503 participants (280 females, 223 males) were administered the Morningness‐Eveningness Questionnaire (MEQ) and the self‐report version of the Big Five Observer (BFO) to determine circadian preference and personality features, respectively. Morning types scored significantly higher than evening and intermediate types on the conscientiousness factor. Evening types were found to be more neurotic than morning types. With reference to the big five personality model, our data, together with those of all the previous studies, indicate that the conscientiousness domain is the one that best discriminates among the three circadian types. Results are discussed with reference to neurobiological models of personality.

COMPARISON OF TWO DIFFERENT ACTIGRAPHS WITH POLYSOMNOGRAPHY IN HEALTHY YOUNG SUBJECTS

The present study aimed to compare two commercially available actigraphs, with a concurrent polysomnographic (PSG) recording. Twelve healthy volunteers (six women; age range 19–28 yrs) simultaneously wore the Basic Mini‐Motionlogger® and Actiwatch® for seven overnight polysomnographic recordings. Comparisons of the following sleep measures were focused on: sleep onset latency (SOL), total sleep time, wake after sleep onset, and sleep efficiency. Both devices underestimated SOL in comparison to PSG, but they had similar performance compared to PSG for the other sleep measures. A limit of the study is that the results can be only generalized to healthy young subjects.

Association between circadian preference and academic achievement: A systematic review and meta-analysis

The association between circadian preference and academic achievement has been assessed through a systematic review and meta-analysis. The literature searches retrieved 1647 studies; 31 studies, with a total sample size of 27 309 participants, fulfilled the inclusion criteria and were included in the meta-analysis. With reference to all these 31 studies, before running the meta-analysis, the sign of the correlation between the investigated variables was set in a way that a positive correlation showed that eveningness was related to worse academic performance. The meta-analysis yielded a small overall effect size of 0.143 (CI [0,129; 0,156]) under a fixed effects model (Z = 20.584, p < 0.001, I2 = 72.656; Q = 109.715) and of 0.145 (CI [0.117; 0.172]) under a random effects model (Z = 10.077, p < 0.001). A random effects model with a grouping variable (participants) revealed 15 studies based on school pupils and 16 on university students. The random model showed a higher effect size in school pupils (0.166, CI from 0.127 to 0.206) compared to university students (0.121, CI from 0.080 to 0.163). Self-report measures of grades revealed a stronger effect size (0.171; CI: 0.137 to 0.206; N = 20) compared to objective measures (0.093; CI: 0.047 to 0.140; N = 19). Overall, the present results suggest that evening orientation is associated with a worse academic performance, both in school pupils and university students; for the first time, it has been shown that such relationship changes over time, being weaker in university students.

Measures of circadian preference in childhood and adolescence: A review

PURPOSE To review the psychometric properties of the questionnaires commonly filled in by children and adolescents to measure circadian preference. METHODS We examined the Morningness-Eveningness Questionnaire for Children and Adolescents (MEQ-CA), the Morningness-Eveningness Scale for Children (MESC) and the Composite Scale of Morningness (CSM). We critically analyzed the reliability, in term of internal consistency (through the Cronbachs alpha) and test-retest reliability (through the correlation coefficient), and the type of validation against external criteria (objective assessment of the sleep/wake cycle, body temperature, hormones and other questionnaires). Fifty studies that reported these data were included in the review: 7 studies used the MEQ-CA, 28 used the MESC and 15 used the CSM. RESULTS The percentage of studies reporting at least acceptable levels of internal consistency was high and similar between the three questionnaires. Evidence for test-retest reliability was scant, since only 3 studies were available; it was at least acceptable for the MESC (two studies with a time interval of 1 month), not acceptable for the MEQ-CA (one study with a time interval of 6 months), while no information was available for the CSM. As regards the validation evidence, the MEQ-CA has been validated by the highest number of external criteria (actigraphy, oral body temperature and other questionnaires), followed by the CSM (cortisol sampling and other questionnaires). The MESC has been validated only against self-report measures. CONCLUSIONS The present state of the art would suggest the use of the MEQ-CA to assess circadian preference in children and adolescents.

Season of Birth and Sleep-Timing Preferences in Adolescents

The aim of the present study was to explore the relationship between season of birth and sleep-timing preferences in adolescence. To this end, the Morningness-Eveningness Questionnaire for Children and Adolescents (MEQ-CA) was administered to 1912 adolescents (1058 females and 854 males), ranging in age between 10 and 17 yrs. To assess preferred sleep habits, the authors considered the answers to the open-ended questions of the MEQ-CA (items 1 and 2), regarding the preferred arising time and the preferred going to bed time. Combining the answers to these two questions, the authors also indirectly computed the preferred sleep duration and preferred midpoint of sleep. Season of birth did not significantly modulate the overall MEQ-CA score; however, spring-born participants preferred to go to bed and reached the preferred midpoint of sleep later than those born in autumn. Agreeing with a previous study on young adults, the present data point to a significant season-of-birth effect on the two parameters of the sleep-timing preferences in adolescents. (Author correspondence: lorenzo.tonetti2@unibo.it)

The Consensus Sleep Diary: Quantitative Criteria for Primary Insomnia Diagnosis

Objective The aim of the study was to put forward quantitative criteria for the Consensus Sleep Diary, to differentiate people with insomnia from normal sleepers. Methods In this retrospective study, we analyzed 295 sleep diaries of patients with primary insomnia (43% were male, ages ranging between 17 and 76 years) collected in two clinical centers for insomnia and 536 sleep diaries of normal sleepers (47% were male, ages ranging between 15 and 82 years). We considered the following sleep parameters: time in bed, sleep onset latency, total sleep time, wake after sleep onset, sleep efficiency, number of awakenings, terminal wakefulness, and subjective feeling of rest. Using the Youden index, we calculated the quantitative criteria that performed best for each sleep parameter. Finally, we created receiver operating characteristic curves to test the accuracy of each identified criterion. Results Individuals with insomnia significantly differed from controls on all sleep indices (p < .001). Differentiation between individuals with insomnia from controls was optimal for terminal wakefulness (>15 minutes, area under the curve [AUC] = 0.83), wake after sleep onset (cutoff >20 minutes, AUC = 0.81), total sleep time (<390 minutes, AUC = 0.80), and particularly sleep efficiency (<87.5%, AUC = 0.92, sensitivity = 0.80, specificity = 0.90). Time in bed was the least differentiating variable (<500 minutes, AUC = 0.57). Conclusions The quantitative criteria of the sleep diary in this study agree with the few available data in the literature. This confirms that the sleep diary could be a useful screening tool for assessing patients with primary insomnia.

Circadian type and mood seasonality in adolescents

The aim of the present study was to investigate, for the first time, the relationship between circadian preference and mood seasonality in adolescents. To this end, 1539 participants (881 female; 658 male) completed the Morningness–Eveningness Questionnaire for Children and Adolescents and the Seasonal Pattern Assessment Questionnaire for Children and Adolescents to determine circadian preference and mood seasonality, respectively. Evening types achieved significantly higher mood seasonality scores than intermediate and morning types, as intermediates did than morning types. Agreeing with previous studies on young adults and adults, the present data indicate a significant relationship between eveningness and higher mood seasonality in adolescents.

Season of birth and personality in healthy young adults

The purpose of this study was to explore a possible season of birth effect on big five personality traits, taking into account also gender and circadian typology variables. A sample of 419 healthy young adults (249 females and 170 males) was administered the self-report version of the Big Five Observer (BFO) and the Morningness -- Eveningness Questionnaire (MEQ) to determine, respectively, personality features and circadian preference. Participants were subdivided into four season groups, according to their birth date. No significant season of birth effect was observed as regards personality traits even if summer-born participants tended to score lower on the conscientiousness dimension. In regard to the conscientiousness domain, there was a significant interaction between gender and season of birth. Males presented greater conscientiousness variation with summer born participants scoring lower. On the basis of a multiple regression analysis, MEQ score proved to be a better predictor of conscientiousness than gender, age, and season of birth. The results provide no clear evidence for a season of birth effect on the big five personality traits. It is possible that circadian preference may modulate the season of birth effect on personality traits.

Effects of sleep timing, sleep quality and sleep duration on school achievement in adolescents

OBJECTIVE The aim of this study was to examine the effects of sleep timing, quality and duration on school achievement in adolescents. METHODS Thirty-six Italian students (mean age: 18.14 ± 0.49 years) attending their last year of high school participated in the study. They completed the Morningness-Eveningness Questionnaire for Children and Adolescents (MEQ-CA). This was used to determine their ideal sleep timing by computing the total score, with higher scores corresponding to a greater tendency toward morningness. In addition, students underwent two non-consecutive weeks of actigraphy in one-month period to objectively assess: habitual sleep timing through the midpoint of sleep (MS); habitual sleep quality through the parameter of sleep efficiency (SE); and habitual sleep duration through the parameter of total sleep time (TST). Participants also completed the Mini Sleep Questionnaire, which allowed us to assess perceived sleep quality, at the end of each actigraphic-recording week. School performance was assessed using the grades obtained by students in their school leaving exams taken at the end of the school year. RESULTS A significant positive correlation was observed between SE and exam grades, as well as MEQ-CA scores and grades. Multiple regression analysis showed that only SE was significantly and positively related to the final grade. CONCLUSIONS Examining objective and ecological measures, SE (indicator of sleep quality) had the strongest effect on school achievement in adolescents.