Circadian System Heritability Assessed in Free Living Conditions

Study Overview
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Brief Summary
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The purpose of this investigation is to assess the role of the genetic and environmental factor on circadian system, in free living conditions by the use of a female twin population. With the results from this study, the investigators expect to advance in the understanding of the role of the endogenicity of the circadian system variables such as temperature, activity, sleep and timing of food intake as the main cause of the coincidence of the rhythms. However, the investigators expected that some parameters are still dependent on environment to a relevant extent and, hence, amenable to change through external interventions.

Detailed Description
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Twin studies are a classic in the analysis of the relative contribution of genetic and environmental factors to behavior and other phenotypes. These models are most often used to separate genetic from environmental causes in the family resemblance methodology. These models based on twins have been previously carried out in chronobiology. In fact, during the years 1993 and 1994, Paul Linkowski et al., performed two relevant studies on the circadian system to analyze the relative contributions of hereditary and/or environmental factors of cortisol secretion and blood pressure, respectively, and concluded that genetic factors control some of the characteristics of cortisol and diastolic blood pressure circadian rhythmicity. The heritability of other circadian markers has also demonstrated such as morningness- eveningness (44%), sleep-related variables have also pointed to a relevant role of genetics with heritability estimates of sleep duration between 17% and 55%. However, to the investigators knowledge, the heritability of other relevant chronobiological markers, measured in free living conditions such as body temperature, actigraphy and sleep has not been studied. These goals will be achieved through a specific approach: Observational (Aim 1): To study the potential effect of the genetic and environmental factor in the circadian system health in order to improve the chronobiological therapies in the clinical practice (n=106).

Official Title
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Circadian System Heritability Assessed in Free Living Conditions in a Twin Mediterranean Population

Conditions
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Healthy

Intervention / Treatment
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* Other: Chronobiological status of the subjects


Participation Criteria
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Eligibility Criteria
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IInclusion Criteria: Body Mass Index: >19 kg/m2 Age: between 18 and 70 year of age Caucasian Exclusion Criteria: Receiving treatment with thermogenic, lipogenic, or contraceptive drugs Diabetes mellitus, chronic renal failure, hepatic diseases, or cancer diagnosis Bulimia diagnosis, prone to binge eating Undergoing treatment with anxiolytic or antidepressant drugs

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 70 Years

Sexes Eligible for Study
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Female

Study Plan
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How is the study designed?
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Arms and Interventions

| Intervention/Treatment |
| --- |
|Other: Chronobiological status of the subjects|Participation was completely voluntary and not remunerated. The subjects were organized into groups of 5 pairs, and were given an appointment at a university facility located in the city center, where informed consent was signed prior to the procedures indicated below. An informational letter was sent to pre-selected individuals. Later a phone call confirmed their availability. Temperature rhythm was assessed continuously for 7 days using a temperature sensor and programmed to collect information every 10 min. Body position and rest-activity rhythm were assessed over the same 7 days using a Acceleration Data Logger that record data every min and placed on the non-dominant arm by means of an elastic band, with its X axis parallel to the humerus bone. Diet and sleep record were completed over the same week, their sleep schedules and their nutritional status.|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Temperature record | Measured using temperature sensor | Total of 1 week between Visit 1 and 2 | 
| Actigraphy record | Measured using Pendant Acceleration Data Logger | Total of 1 week between Visit 1 and 2 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Light record | Measured using Pendant Acceleration Data Logger | Total of 1 week between Visit 1 and 2 | 
| Sleep record | Measured using Pendant Acceleration Data Logger | Total of 1 week between Visit 1 and 2 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Chronobiology, Circadian rhythms, Heritability, Twins