Cortisol response to awakening: what it is, how it works and what it is for

Throughout the day our levels of the hormone cortisol are different, with two times when there is an increase: at night and shortly after we wake up.

The cortisol response upon awakening It is a phenomenon that occurs shortly before an hour has passed since we woke up and that seems to be related to stress and the ability to cope with the demands of day-to-day life.

Below we will take a closer look at what this phenomenon consists of, what are its neurological correlates, what factors seem to influence its intensity, and what health problems seem to be linked to a cortisol response to irregular awakening.

What is the cortisol response on waking?

Throughout the day, people have different levels of cortisol. There are two moments in which this hormone is increased: at night, and in the morning, shortly after waking up. The cortisol response to awakening is a neurophysiological phenomenon that occurs within the first hour after awakening.. It consists of an increase between 38% and 75% of the hormone cortisol, normally after about 30 or 45 minutes after waking up in the morning.

Because the hormone involved in this phenomenon is closely related to stress, it has been suggested that this phenomenon could have the main function of activating us to cope with the demands of day to day. Also, it is believed that there are several factors that influence the appearance of this phenomenon, including the time we wake up, environmental factors such as lighting and, also, presenting stress throughout the day, associated with injury or illness.

How does it seem?

When we wake up and after a few minutes, people present an increase in the hormone cortisol. The percentage of this hormone in the blood increases between 38% and 75%, with an increase of 50% being normal.. This is easily verifiable by analyzing the saliva of a person, in which their average salivary cortisol level is 15 nmol / l as soon as they get up but, after about 30 or 45 minutes, it has increased reaching 23 nmol / l, although, of course, there are people who have higher increases and others who have them smaller or, even, tiny.

The cortisol response upon awakening reaches its maximum peak 45 minutes after awakening, remaining increasing by about 35% during the following hour. This response pattern is relatively stable in all people, as long as there are no pathology or sociocultural factors that induce high stress.

In addition, it has been seen that it has a strong genetic factor, finding in studies with monozygotic twins a heritability value close to 0.40.

But despite the fact that it supposes a great increase of this hormone, the response of cortisol when waking up is not the highest that occurs throughout the day. The moment in which there is a greater secretion of cortisol occurs during the second half of the night while we are sleeping.

This phenomenon, associated with circadian cycles, can occur very few hours before the cortisol response upon awakening, as long as the person gets up early, between 6 a.m. and 9 a.m.

You have to understand that the increase in cortisol at night and that associated with awakening are independent of each other, even though the same hormone is involved. After both increases have occurred, cortisol levels fall throughout the day, reaching the lowest point during the first half of the night, just before the nocturnal increase of this hormone.

Neurological mechanisms

Cortisol is a hormone that is released in the adrenal glands upon activation of the pituitary gland by adrenocorticotropic hormone (ACTH). ACTH release induces the cortisol response on awakening, which triggers glucocorticoid production.

It has been seen that ACTH is a hormone that is inhibited after the presence of dexamethasone, a synthetic glucocorticoid, which explains that after the increase in cortisol and the release of glucocorticoids, it stops being secreted.

ACTH release is regulated by the hypothalamus on the hypothalamic-pituitary-adrenal axis. The hypothalamus releases the hypophysiotropic hormone, a hormone that causes corticotropin to be released, the production of which is subject to the influence of the circadian day / night cycle.

However, the cortisol response on awakening is controlled by the hippocampus on the hypothalamic-pituitary-adrenal axis. This has been proven in people who have a damaged hippocampus, either due to unilateral or bilateral injury or atrophy, presenting low levels of cortisol shortly after waking up or, directly, without any increase. Instead, people with a healthy, larger-than-normal hippocampus have a greater cortisol response on waking.

Variables and influencing factors

Several factors influence the cortisol response upon awakening. These factors can both increase cortisol levels and significantly reduce them, apparently influencing the ability to cope with the demands of everyday life.

Environmental / behavioral

The cortisol response to awakening is a phenomenon that occurs only and directly to the fact of awakening. However, the time we wake up seems to influence the increase in the hormone in the blood, being that the sooner we wake up, the greater the increase will be, as long as it is done in the morning and after having given the increase in cortisol at night.

An example of how the time we wake up influences this is in the case of health personnel, who due to their type of work have irregular work shifts and must be on duty. In one study, it was found that nurses who had to wake up between 4 a.m. and 5.30 a.m. had higher levels of the hormone cortisol upon waking than those who had to wake up at 6 a.m. or 9 a.m. Those who had to wake up at 11 a.m. am – 2 pm they had very low levels.

It has been seen that lighting upon awakening influences response. People who wake up in a bright room, such as when the first rays of the sun enter, have a greater increase in the cortisol response than those who wake up in total darkness. On the other hand, waking up to the alarm clock or spontaneously does not influence the increase in morning cortisol.

Another factor that influences the increase in cortisol is in naps. It has been seen that taking a nap of one or two hours during the first hours of the afternoon (6.45 pm – 8.30 pm) does not induce the cortisol response on waking, it being seen that this phenomenon can only occur after having slept at night.

Individuals

Being a day or night person influences this response. Daytime people, that is, those who are most active during the first hours of the day, have a greater cortisol response upon waking than at night, which would explain why these types of people tend to be more productive during daylight hours.

People who have some type of disease or injury that causes them a lot of pain may have affected cortisol levels and, consequently, the response of cortisol upon awakening. Based on some research, the more pain the patient suffers, the more reduced the cortisol response upon awakening.

Another very interesting aspect is the socioeconomic aspect. It has been seen that people with lower socioeconomic status have a higher cortisol response upon waking. This can be directly explained by the fact that people with low incomes and more social problems live more stressed, having to try harder to make it to the end of the month and at the same time being more sensitive to suffering from psychopathology.

Possible function

Much research has linked the response of cortisol on awakening to chronic stress, suggesting that it has a specific role in preparing the body to cope with the demands of everyday life.

Although this is still an uncertain belief, it is believed that an increase in cortisol in the morning It would be related to a greater activation and availability of resources to be able to satisfy the demands of the day to day. The availability of glucocorticoids associated with this phenomenon allows you to have energy to be able to do tasks throughout the day.

The more tasks that have to be done, the more cortisol is secreted shortly after waking up. A person who knows that he has a lot to do begins to feel cognitively preoccupied with the tasks he has to do, that is, he anticipates the stress that will keep him awake while performing the activity that he must complete. Thus, anticipatory stress is a strong cognitive and internal stressor that increases cortisol associated with the cortisol response upon awakening.

In short, the cortisol response upon awakening has an adaptive functionality, which provides the individual with the necessary energy to meet anticipated demands you have to do throughout the day. The more tasks we have to do, the more cortisol will be released after getting up and, consequently, the more prepared we will be to fulfill the tasks of our day to day.

Problems related to this phenomenon

Several studies have found a relationship between having a cortisol response to irregular awakening and having health problems. As we have commented, there are several factors that mediate blood cortisol levels and, therefore, how the cortisol response occurs upon awakening, with both environmental, internal or personal factors.

Regardless of what it is that alters the levels of this hormone, we can speak of several pathologies associated with both high and low levels of cortisol.

High cortisol responses on awakening have been found in multiple sclerosis, respiratory problems, visceral obesity and, in women, metabolic syndrome. Additionally, having high cortisol on waking appears to be associated with an increased risk for peritraumatic dissociation and acute stress disorder, along with the possibility of developing depression. Low levels are present in problems such as type 2 diabetes mellitus, chronic fatigue syndrome, systemic hypertension and functional digestive disorder.

Bibliographic references:

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