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 moments in which 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.

Next, we are going to 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 on waking irregular.

• Related article: "Cortisol: the hormone that causes us stress"

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 face the demands of the day to day day. Also, it is believed that there are several factors that influence the appearance of this phenomenon, including the time in which we we wake up, environmental factors such as lighting and, also, present stress throughout the day, associated with injury or disease.

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 a person's saliva, 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, naturally, there are people who have greater increases and others who have them milder or even miniscule.

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 wakes up early, between 6 a.m. Y 9 a.m.

You have to understand that the increase in nocturnal cortisol 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 nightly increase of this hormone.

• You may be interested in: "Circadian rhythms: what are they and in what biological functions do they intervene"

Neurological mechanisms

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

ACTH has been shown to be 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 influenced by 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 by 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 the levels of the hormone cortisol and reduce them. significantly, apparently influencing the ability to cope with the demands of the day to day.

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 we have in the case of staff health workers, who due to their type of work have irregular work shifts and must do guards. In one study, nurses who had to wake up between 4 a.m. and 5:30 a.m. had levels of the hormone cortisol wake up older than those who had to do it at 6 a.m. or 9 a.m. Those who had to wake up at 11 a.m. - 2 p.m. they had very levels low.

It has been seen that lighting upon awakening influences response. People who wake up in a bright room, such as the entrance of the first rays of the sun, have a greater increase in 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. Taking a one or two hour nap during the early afternoon (6.45 p.m. - 8.30 p.m.) has been found not to induces the cortisol response on waking, seeing that this phenomenon can only occur after having slept due to the 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 illness 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 waking.

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 may be directly explained by the fact that people with low incomes and more social problems live longer. stressed, having to work harder to make ends meet and at the same time being more sensitive to suffering psychopathology.

Possible function

Much research has linked the cortisol response to awakening to chronic stress, which has fact that it is suggested that it has the specific function of preparing the organism to face the demands everyday.

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 cognitive concern about the tasks that he has what to do, that is, you anticipate the stress that will keep you awake while doing the activity you should comply. 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 the levels of cortisol in the blood and, therefore, in how the cortisol response is produced upon awakening, having both environmental and internal factors or personal.

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. Also, having high cortisol on waking seems to be associated with an increased risk for peritraumatic dissociation and acute stress disorder, along with the possibility of presenting 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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