Effects of Environmental Factors on the Endocrine System
George H. Gass, Harold M. Kaplan in Handbook of Endocrinology, 2020
Similar to the difference between the definitions of “diurnal” and “circadian,” “seasonal” is not equivalent to “circannual.” Seasonality refers to the seasonal responses of animals to the annual cycle. In most seasonal mammalian species, their annual reproductive cycles are truly driven by the endogenous circannual rhythm synchronized with the annual cycle. Natural selection favors such a synchrony because it provides a mechanism to time an appropriate set of environmental conditions for reproduction. It has been suggested that all different forms of mammalian seasonality evolved from a single ancestral mechanism for annual timekeeping.21 Because it is regulated mostly by a photoperiodic mechanism, this annual timekeeping mechanism is linked with the circadian oscillator.
Iterated Filtering Methods for Markov Process Epidemic Models
Leonhard Held, Niel Hens, Philip O’Neill, Jacco Wallinga in Handbook of Infectious Disease Data Analysis, 2019
Seasonality. For many diseases such as childhood diseases or vector borne diseases the transmission rate is not constant but varies through time. This might be due to social aggregations of the host such as in daycare institutions and schools which are closed during summer, changes in environment that influence the biology of vector populations or changes in weather such as temperature or precipitation. One way to introduce this complexity into our models is through seasonal forcing of the transmission rate so that the number of infectious contacts changes through time as . Following Keeling and Rohani (2008), one possible choice is where is the amplitude of the forcing, is the period of the forcing and is the phase shift parameter. With this choice of forcing function the parameter can be interpreted as the average transmission rate of an individual which varies between and during the forcing period.
Food quality
Pamela Mason, Tim Lang in Sustainable Diets, 2017
A study commissioned by the UK Department for Environment, Food and Rural Affairs (Defra) proposed two definitions of seasonal food, the first based on where the food is produced, and the second on where it is produced and consumed.49 In the first definition, food is grown or produced outdoors during the natural growing/production period for the country or region where it is produced. It need not necessarily be consumed locally to where it is produced. This is defined as global seasonality. Apples grown in season naturally outdoors in New Zealand and eaten in Europe in the spring and summer by this definition would be globally seasonal. In the second definition, food is produced and consumed in season and in the same climatic zone without high energy use or storage. This is described as locally seasonal food, but this leads to a further debate on what constitutes ‘local’. For example, are raspberries grown in season in Scotland and consumed in Wales locally seasonal? The most important aspect of both these definitions of seasonality is that the food is grown or produced outdoors in its natural season without the use of additional energy, thereby not creating additional greenhouse gas emissions.
Seasonal variations of changes in lipid and glucidic variables after bariatric surgery
Published in Chronobiology International, 2019
Trinitat Cambras, Eva Pardina, Júlia Carmona, David Ricart-Jané, Antonio Miñarro, Roser Ferrer, Albert Lecube, José María Balibrea, Enric Caubet, Oscar González, Ramón Vilallonga, Jose Manuel Fort, Elena Cuello, Juan A. Baena-Fustegueras, Antoni Díez-Noguera, Julia Peinado-Onsurbe
Seasonality is a phenomenon characterized by changes along the year in sleep, mood, behaviour, appetite, food preferences and body weight. In most living beings these seasonal changes, such as those that occur in hibernating animals, are an adaptive strategy to save energy in winter. Although seasonality is considered reductional in humans and even more attenuated in modern society, several variables have been reported to change throughout the year. Seasonal fluctuations in humans (Kantermann et al. 2007) have been described in population behaviours, such as conception and suicide (Davis et al. 2010; Foster et al. 2013), but also in such functions as calorie intake or cholesterol levels (Meyer et al. 2016; Gordon et al. 1987). Seasonal affective disorder, which has been described in many temperate regions, reflects an extreme of normal seasonal variation and produces such symptoms as hypersomnia, increased of appetite and weight gain (Rosenthal et al. 1984; Rintamäki et al. 2008).
A longitudinal large-scale objective sleep data analysis revealed a seasonal sleep variation in the Japanese population
Published in Chronobiology International, 2018
Masanori Hashizaki, Hiroshi Nakajima, Toshikazu Shiga, Masakazu Tsutsumi, Kazuhiko Kume
As for statistical analysis, we approximated all the individual night data with the linear mixed-effects regression fitting for seasonality (sine and cosine), age, type of day (weekdays and weekend days), and sex (Matthews et al. 2001; Ma et al. 2006). All sleep parameters for each night were adjusted using coefficients of the independent variable (age, type of day, and sex) and random effects for intercept (each user). The baseline values were set at 50 years old, weekday, and male, because of the largest attribution in our data. Input data for seasonal parameters are the date. There are two kinds of seasonal change, namely single peak seasonality and two peaks seasonality in a year. Therefore, we set two cycle parameters in sine and cosine, 2/365 days for single peak seasonality, 2/365 days and 4/365 days for two peaks seasonality. For phase analysis of sleep parameters, maximum and minimum values were calculated from the model. The approximate equation contains five parameters for four factors as below:
Is being born in spring significantly associated with early-onset bipolar affective disorder? A case-control study
Published in Chronobiology International, 2020
Meng-Qi Wang, Yu Hao, Ran-Ran Wang, Hua Guo, Juan He, Zhi-Ren Wang
Seasonality dominates many features of the global environment, and it is also believed to influence human health. Seasonal factors can potentially even exert influence before birth, and accumulating evidence suggests that environmental factors pertaining to early life including placental dysfunction (Suda and Takei 2011), maternal malnutrition during pregnancy (Moody et al. 2017), psychological distress during pregnancy (Suda and Takei 2011), light exposure (Bauer et al, 2015), and infections during both the gestational and postnatal period (Barichello et al. 2016; Marangoni et al. 2016) are associated with alterations in gene expression regulated by epigenetic factors. Thus, such things may affect susceptibility to neuropsychiatric diseases in later life (Suda and Takei 2011).
Related Knowledge Centers
- Photoperiodism
- Time Series
- Seasonal Adjustment
- Dependent & Independent Variables