Biological rhythms: definition, types and operation

Surely all of us have heard at some point in our lives that people are animals of habit. This expression, in addition to being true, hides an infinity of processes that our body carries out to keep these habits at bay.

These processes refer to the biological rhythms, which determine practically all the main activities of our body, from the need for sleep, the sensation of hunger or the rhythm with which we blink.

Related article: "The 9 stages of life of human beings"

What are biological rhythms?

Biological rhythms are understood as the oscillations that occur in physiological levels and variables within a time interval, These oscillations depend on an internal timer or clock and on external or environmental variables that intervene in their synchronization.

Both human and animal habits and activities always present a regular cadence and harmony. To put it in some way, living implies a rhythmic phenomenon that marks us when to eat, when to drink, when to sleep, etc.

In this way, if we stop to think about the relationship between a bodily custom or habit and its relationship with time

, we will be able to observe that all of them occur in a cyclical order or cadence which makes us think that there is something in our organism, or outside of it, that is in charge of regulating them.

The external agents that regulate our daily habits are much more common than is sometimes thought. The environment, seasonal changes, daylight hours or cosmic changes such as lunar phases play a very important role in regulating the activities of our body.

The main internal structures involved in this regulation are the nervous system and the endocrine system, which are influenced by these external agents. However, there are a number of internally controlled rhythms such as heart rate or breathing times, this other type of rhythms should be classified in a separate group due to their character endogenous.

Types of biological rhythms and functionality

As mentioned above, chronobiology distinguishes up to three types of biological rhythms according to their duration. These rhythms are called: circadian, infradian and ultradian..

1. Cardiac rhtyms

Taking into account the etymological origin of this term: circa-around and dies-day; we can correctly assume that circadian rhythms are those bodily needs or habits that occur every 24 hours about.

The best known and illustrative example is sleep cycles. Usually the need for sleep always appears at the same hours and any alteration of this rhythm sometimes implies some type of disorder or sleep disorder.

If we take this example into account, it is not unusual to think that these habits depend largely on external regulatory agents such as daylight. Hence, it is always recommended to sleep in complete darkness because even artificial light can alter our sleep cycles.

Such is the influence of these exogenous regulators that they even influence the course of some diseases or psychological conditions. In the case of depression disorder It is common for people to report a worsening of psychological symptoms during the first hours of the day, which moderate throughout the day.

2. Infradian rhythms

By infradian rhythms we understand all those habits and activities of the body that occur with a cadence of less than 24 hours, that is, less than once a day. Although this may seem strange, there are certain body habits that work with these oscillations.

The most common example is the menstrual cycle, since it completes once every 28 days. Other phenomena that occur with a cadence similar to that of the menstrual cycle are the lunar cycles and the tides, hence in Many times it has been tried to establish an influence of the lunar phases in the different stages of the cycles of the women.

However, this relationship has never been scientifically proven. Those who defend it justify this impossibility on the basis that there are many day-to-day factors that interfere with the coordination of both rhythms.

3. ultradian rhythms

Although less well known and less subject to external influences, there are a series of rhythmic movements that occur with a frequency of more than one every twenty-four hours.

These rhythms are the heartbeat, blinking, the rhythm of breathing, or the REM cycles of sleep. that occur every 90 minutes.

How to maintain biological rhythms

As mentioned above, given that these biological rhythms are conditioned by numerous external and environmental factors, they can be easily altered as a result of any change, either in the environment or due to a change in our routine daily.

To avoid the possible consequences of these variations in our biological rhythms (insomnia, changes in mood, changes in appetite, etc.) It is convenient to maintain a daily routine that allows us to maintain our energy.

Below are a series of recommendations to keep our biological rhythms intact.

1. Get up and go to bed at the same time

As far as possible, it is convenient both to start and end our day always at the same time or, at least, at approximate times. The moment we wake up marks the beginning of the activation phase of our bodies.

However it is also a minimum amount of sleep is required. That is, if one day we go to bed later than usual for whatever reason, it is better to do the 7 or 8 hours of sleep recommended rather than getting up too early just to meet the schedule.

2. Maintain routine even on vacation

Although it may seem unappetizing, it is advisable to maintain our regular hours even during the holidays. In this way we will keep our biological rhythms practically intact and it will be much easier for us to conserve energy once they are finished and we have to return to the routine.

If necessary, a relatively structured schedule can be set up in advance, so that the increase in free time does not cause us to postpone tasks whose regularity must be enhance.

3. Always eat at the same time

Like sleep, the sensation of hunger is also subject to a temporal cadence. Furthermore, all biological functions depend on how and when we nourish ourselves, so that failures in the diet and in the regularity with which we eat can create a chain effect. Therefore, it is essential to maintain stable times for main meals. Thus, we will have controlled the sensation of hunger and we will avoid binge eating.

4. Keep an agenda or diary with our habits

If we monitor our daily activities or habits, it will be easier for us to fulfill all those obligations or objectives that we set for ourselves on a day-to-day basis. Therefore, avoiding imbalances and pronounced irregularities in the organization of our week will favor the establishment of healthy and consistent biological cycles.

Bibliographic references:

• Ashoff, J. (ed.) (1965). Circadian Clocks. Amsterdam: North Holland Press.
• Richter, H.G., Torres-Farfán, C., Rojas-García, P.P., Campino, C., Torrealba, F., Serón-Ferré, M. (2004). The circadian timing system: making sense of day/night gene expression. Biol Res.;37(1):11-28.
• Takahashi, J.S., Zatz, M. (1982). Regulation of circadian rhythmicity. Science. 217 (4565): 1104–11.