July 24, 2020 By RJ

Chronobiology is the branch of biology concerned with cyclical physiological phenomena.It is the study of mechanisms underlying chronomes, structures in time, found in organisms, in populations, and in the environment. Chronobiology  describes everyday physiology under ordinary conditions as well as after the standardization or constancy, as far as possible, of environmental temperature, lighting, the availability of food and other manipulable local conditions, while consulting records of as yet mostly unalterable variability in space


Factors of Sleep Physiology

  • The long-term studies commonly used in biologic rhythm research precluded continuous recording of brain wave activity. Certainly, in the early days, the latter was far too difficult and not really necessary. The measurement of wheel-running activity was a convenient and widely used method for demonstrating circadian rhythmicity.
  • The favorite animal of sleep research from the 1930s through the 1970s was the cat, and neither cats nor dogs demonstrate clearly defined circadian activity rhythms.
  • The separation between chronobiology and sleep research was further maintained by the tendency for chrono­biologists to know very little about sleep, and for sleep researchers to remain ignorant of such biologic clock mysteries as phase response curves, entrainment, and internal desynchronization.

Chronobilogical Rythms

1.Circadian rhythms: The natural cycle of physical, mental, and behavior changes that the body goes through in a 24-hour cycle. Circadian rhythms are mostly affected by light and darkness and are controlled by a small area in the middle of the brain. They can affect sleep, body temperature, hormones, appetite, and other body functions. Abnormal circadian rhythms may be linked to obesity, diabetes, depression, bipolar disorder, seasonal affective disorder, and sleep disorders such as insomnia. Circadian rhythm is sometimes called the body’s clock.

2.Diurnal rhythms: A retrospective clinical study on the sleeping habits of patients with macular degeneration was conducted to test the hypothesis that alterations in cone outer segment shedding cycles might be important in the pathogenesis of this disease. No significant difference in number of hours of sleep per night, frequency of nighttime awakening, or frequency of daytime napping was found between patients with macular degeneration and controls. This finding does not support the hypothesis at this level of inquiry.


Chronobiology and Nutrition

Numerous long-term studies have investigated the circadian clock system in mammals, which organizes physiological functions, including metabolism, digestion, and absorption of food, and energy expenditure. Food or nutrition can be a synchronizer for the circadian clock systems, as potent as the external light–dark signal can be.

Recent studies have investigated different kinds of food, frequency of consumption, and time of consumption for optimizing body clock and ensuring healthy habits. In this review, we discuss recent studies investigating chronobiology and nutrition, and then summarize available information as “Chrono-nutrition” for the development of a new standardized research strategy.

Chronobiology and Diet

Recent research in chronobiology reveals that there are two dietary factors that can affect the body’s rhythm. What is eaten combined with when foods are eaten ultimately affect the person’s internal clock. The body’s key organs function at their best during certain times of the day. Studies show that it is possible to train the body by eating certain meals at certain times each day to improve the body’s digestive performance and reduce the risk of gastrointestinal issues.

Chronobiology: how meal times can affect body weight

In mammals, there is a biological clock in the hypothalamus which is synchronised with the stimuli of light and darkness. There are also clocks in peripheral tissues which can be modulated by the central clock and by food.

  • In the morning, the central clock alarm sounds and cortisone, the waking-up hormone, is activated; it travels through the blood to set the time schedule for tissues and organs.
  • In the afternoon, the body temperature rises slightly and then drops at night. This is a sign for the body clock to prepare itself for rest.
  • The adipose tissue shows a circadian rhythm. Its clock genes are able to regulate the rhythmic expression of the hormones which determine appetite and weight, such as adiponectin, leptin and resistin.