Whereas most people require more than 6 h of sleep to feel well rested, there appears to be a group of people who can function well on between 3 and 6 h of sleep. The aims of the present study were to compare 12 naturally short (3-6 h) sleepers (9 males 3 females, mean age 39.6 years, SD age 10.1 years) recruited by a media publicity campaign with age, gender and chronotype matched medium lengt...

INTRODUCTION The human circadian timing system generates multiple circadian rhythms. One of the characteristics of a rhythm is the phase. The circadian phase could be defined as the time at which the circadian rhythm of a variable reaches a particular state (Van Dongen, 1998). Substantial inter-individual differences in the circadian phase of several variables have been observed (Foret, 1982; K...

The human circadian rhythmicity is an internal biological clock mechanism that enables them to effectively perform tasks during a particular time of the day, due which they exhibit diurnal effects. morningness-eveningness questionnaire classifies individuals as definitely morning, moderately intermediate, evening, and evening type based on their active performance different times day. Literatur...

Studies have shown that Evening-Type (ET) subjects used more stimulating and sedative substances, and presented more psychiatric disorders than Morning-Type (MT) subject. However, there is a lack of data on the chronotype of patients with addiction. The aim of our study was to describe chronotype and associated factors in a sample of outpatients beginning treatment for addiction. Subjects were ...

A single nucleotide polymorphism located in the 3' flanking region of the human CLOCK gene was investigated as a predictor of diurnal preference in a population-based random sample of 410 normal adults. Morningness-eveningness preferences were determined using the 19-item Home-Ostberg questionnaire. Subjects carrying one of the two CLOCK alleles, 3111C, had a significantly lower mean Horne-Ostb...

Background: The identification of differences in seasonality and chronotype may provide useful information regarding unipolar mania as a distinct entity. Therefore, the present study was planned to compare seasonality and chronotype in patients with unipolar mania and bipolar disorder. Method: A cross-sectional study included 60 euthymic outpatients, 30 affected by bipolar affective disorder (b...

Many teenagers go to bed and wake up significantly later than younger children, a developmental progression thought to reflect adolescent psychosocial processes. To determine whether biological processes may underlie a delay of phase preference in adolescents, 183 sixth-grade boys and 275 sixth-grade girls completed questionnaires for morningness/eveningness (M/E) and pubertal status. School en...

The purpose of this study was to investigate the influence of shift work and chronotype on the quality of life of nursing staff at a university hospital in the state of Rio Grande do Sul, Brazil. It is an analytical and cross-sectional study, developed with a sample of 101 nursing professionals working in clinical and surgical units for adult inpatients. Chronotype and quality of life were eval...