We investigated salivary cortisol profiles in the first hour after awakening in morning versus evening chronotypes. Chronotypes were defined by Horne and Ostberg's Owl-and-Lark-Questionnaire. In a sample of 112 healthy, day-active young men, we identified 9 morning and 29 evening chronotypes. Saliva samples were collected 0, 30, 45, and 60min after awakening on 2 consecutive days. Log-transformed cortisol levels were analyzed with General Linear Model procedures (GLMs) and awakening time and sleep duration were entered as covariates. On both days, a significant main effect of chronotype emerged (both p=0.02), and this effect could not be explained by differences in awakening time or sleep duration. The present data support the idea that morning relative to evening chronotypes might show higher cortisol levels in the first hour after awakening. In sum, individual chronotype should be acknowledged as one further possible source of interindividual variability in the cortisol rise after awakening.
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http://dx.doi.org/10.1016/j.biopsycho.2005.08.003 | DOI Listing |
Eur Spine J
January 2025
Department of Orthopedics, the Seventh Affiliated Hospital, Sun Yat-sen University, Shenzhen, 518000, Guangdong, China.
Objectives: Sleep disorders are considered a risk factor for aging and skeletal degeneration, but their impact on intervertebral disc degeneration (IDD) remains unclear. The aim of this study was to assess associations between sleep characteristics and IDD, and to identify potential causal relationships.
Methods: Exposure factors included six unhealthy sleep characteristics: insomnia, short sleep duration (< 7 h), long sleep duration (≥ 9 h), evening chronotype, daytime sleepiness, and snoring.
Ind Health
January 2025
Andong Science College, Department of Nursing, South Korea.
The ability to adapt to night shift work varies greatly among individuals, but little is known about how personal traits and coping strategies interact to affect shift-work tolerance. This study aimed to identify how certain personal traits (e.g.
View Article and Find Full Text PDFPhilos Trans R Soc Lond B Biol Sci
January 2025
Institute of Medical Psychology, LMU Munich, Munich 80336, Germany.
Sleep deficiency is associated with infectious disease risk. However, little is known about the individual roles of different aspects of sleep, including sleep duration, sleep quality, sleep timing (assessed by chronotype) and sleep regularity (in the form of social jet lag) in this context. Here, we examined associations of the probability of reporting a cold or other infections with self-reported sleep duration, sleep quality and chronotype in a sample of 642 adults, and with social jet lag in a subsample of 274 adults.
View Article and Find Full Text PDFChronobiol Int
January 2025
Norwegian Competence Center for Sleep Disorders, Haukeland University Hospital, Bergen, Norway.
Epidemiological studies show a high prevalence of "insomnia" in adolescents. However, insomnia symptoms are not specific for insomnia disorder. Puberty is associated with circadian delay, which may cause insomnia symptoms such as problems falling asleep and daytime impairments, but also difficulties rising in the morning which is not a hallmark of insomnia disorder.
View Article and Find Full Text PDFJ Sleep Res
January 2025
Department of Neurology, University of Washington School of Medicine, Seattle, Washington, USA.
Changes in social zeitgebers across the lifespan affect the interaction between biological and social clocks, potentially contributing to social jetlag. Extant literature suggests a reduction in social jetlag given declining social obligations occurring after retirement, but is limited to self-reported methods and cross-sectional designs. Leveraging longitudinal and ecologically valid data from consumer sleep technology, we analysed objective sleep data from 2439 users of the polysomnography-validated SleepScore mobile application, encompassing 500,415 total nights recorded.
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