Cortisol awakening response: what is it, how does it work and what is it for?

Let's see what is the cortisol awakening response and what are its characteristics.

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

The cortisol response upon awakening is a phenomenon that occurs shortly before one hour after waking up and seems to be related to stress and the ability to cope with the demands of everyday life.

We will now take a closer look at what this phenomenon consists of, what its neurological correlates are, what factors seem to influence its intensity and what health problems seem to be linked to an irregular wake-up cortisol response.

What is the cortisol response upon awakening?

Throughout the day, people have different levels of cortisol. There are two times when this hormone is increased: at night, and in the morning, shortly after waking up. The cortisol awakening response is a neurophysiological phenomenon that occurs during the first hour after waking up.. It consists of an increase of between 38% and 75% of the hormone cortisol, usually 30 to 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 may have as its main function to activate us to cope with the demands of everyday life. It is also 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 stress throughout the day, associated with injury or illness.

How does it appear?

When we wake up and after a few minutes, people present an increase of the hormone cortisol. The percentage of this hormone in the Blood increases between 38% and 75%, with a normal increase of 50%.. This is easily verified by analyzing the saliva of a person, in which the average level of salivary cortisol is 15 nmol/l upon waking up but, after 30 or 45 minutes, it has increased to 23 nmol/l, although, naturally, there are people who have greater increases and others who have milder or even minuscule increases.

The cortisol response upon awakening peaks 45 minutes after awakening and remains increased by about 35% for the next hour. This response pattern is relatively stable in all individuals, as long as there is no pathology or sociocultural factors that induce elevated stress.

In addition, it has been found to have a strong genetic factor, with monozygotic twin studies finding a heritability value of about 0.40.

But although it is a large increase in this hormone, the cortisol response upon awakening is not the greatest that occurs throughout the day. The time of greatest cortisol secretion occurs during the second half of the night while we are asleep..

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

It should be understood that the nocturnal cortisol increase and that associated with awakening are independent of each other, even though the same hormone is involved.although the same hormone is involved. After both surges have occurred, cortisol levels decrease 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 released in the adrenal glands following activation of the pituitary gland by adrenocorticotropic hormone (ACTH). ACTH release induces the cortisol response upon awakening, which triggers glucocorticoid production..

It has been shown that ACTH is a hormone that is inhibited in the presence of dexamethasone, a synthetic glucocorticoid, which explains why after the increase in cortisol and the release of glucocorticoids it is no longer secreted.

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

However, the awakening cortisol response is controlled by the hippocampus in the hypothalamic-pituitary-adrenal axis. This has been proven in people whose hippocampus is damaged, either by uni- or bilateral lesion or atrophy, presenting low cortisol levels shortly after waking up or, directly, no increase at all. In contrast, people with a healthy hippocampus people with a healthy hippocampus of larger than normal size have a greater cortisol response upon awakening..

Variables and influencing factors

Several factors influence the cortisol response to awakening. These factors can either increase cortisol hormone levels or significantly reduce them, apparently influencing the ability to cope with day-to-day demands.

Environmental/behavioral

The cortisol response to awakening is a phenomenon that is uniquely and directly related to the act of awakening. However, the time at which we wake up seems to influence the increase of the hormone in the blood.The earlier we wake up, the greater the increase, as long as it is done in the morning and after the nocturnal cortisol increase.

An example of how the time at which 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 call. 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 awakening than those who had to wake up at 6 a.m. or 9 a.m. Those who had to wake up at 6 a.m. or 9 a.m. had higher levels of the hormone cortisol upon awakening. Those who had to wake up at 11 a.m. or 2 p.m. had very high levels of the hormone cortisol. - 2 p.m. had very low levels.

It has been shown that The illumination at the time of awakening has been found to influence the response to. People who wake up in a brightly lit room, such as by the first rays of sunlight, have a greater increase in the cortisol response than those who wake up in total darkness. On the other hand, waking up with the alarm clock or spontaneously does not influence the increase in morning cortisol.

Another factor that influences the increase in cortisol is napping.. It has been shown that taking a nap of one or two hours during the early afternoon (6.45 p.m. - 8.30 p.m.) does not induce the cortisol response upon awakening, it being seen that this phenomenon can only occur after having slept at night.

Individuals

Being a diurnal or nocturnal person influences this response. Diurnal people, i.e. those who are more active during the first hours of the day, have a greater cortisol response upon awakening. than nocturnal ones, 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 involves a lot of pain may have affected cortisol levels and, consequently, the cortisol response to awakening. Based on some research, the more pain the patient is in, the more reduced the cortisol response to awakening will be.

Another very interesting aspect is the socioeconomic aspect. It has been found that people who have a lower socioeconomic status have a higher cortisol response upon awakening.. This can be directly explained by the fact that people with low incomes and more social problems live more stressed, having to work harder to make ends meet and at the same time being more sensitive to suffer from psychopathology.

Possible role

Much research has linked the wake-up cortisol response to chronic stress, which has led to the suggestion that it has the specific function of preparing the body to cope with daily demands.

Although this is still an uncertain belief, it is thought that an increase in cortisol in the morning would be related to a greater activation and availability of the body to cope with daily demands. would be related to a greater activation and availability of resources to be able to meet the demands of everyday life.. The availability of glucocorticoids associated with this phenomenon allows energy to be available to perform 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 worry about the tasks he has to do, i.e., he anticipates the stress that will keep him awake while performing the activity he has to accomplish. Thus, anticipatory stress is a strong cognitive and internal stressor that increases cortisol associated with the cortisol awakening response.

In short, the cortisol awakening response has an adaptive functionality, which provides the individual with the necessary energy. has an adaptive functionality, which provides the individual with the energy needed to meet the anticipated demands demands that have to be made throughout the day. The more tasks we have to do, the more cortisol will be released after waking up and, consequently, the more prepared we will be to accomplish our daily chores.

Problems related to this phenomenon

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

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

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

Referencias bibliográficas:

• Powell, D. J., & Schlotz, W. (2012). Daily life stress and the cortisol awakening response: testing the anticipation hypothesis. PloS one, 7(12), e52067. https://doi.org/10.1371/journal.pone.0052067
• Elder, Greg J.; Wetherell, Mark A.; Barclay, Nicola L.; Ellis, Jason G. (2014). "The cortisol awakening response – Applications and implications for sleep medicine". Sleep Medicine Reviews. 18 (3): 215–224. doi:10.1016/j.smrv.2013.05.001. PMID 23835138.
• Wüst S, Wolf J, Hellhammer DH, Federenko I, Schommer N, Kirschbaum C (2000). "The cortisol awakening response - normal values and confounds". Noise Health. 2 (7): 79–88. PMID 12689474. Archived from the original on 2017-12-01. Retrieved 2009-08-22.
• Wilhelm I, Born J, Kudielka BM, Schlotz W, Wüst S (2007). "Is the cortisol awakening rise a response to awakening?". Psychoneuroendocrinology. 32 (4): 358–66. doi:10.1016/j.psyneuen.2007.01.008. PMID 17408865. S2CID 25044761
• Schmidt-Reinwald A, Pruessner JC, Hellhammer DH, Federenko I, Rohleder N, Schürmeyer TH, Kirschbaum C (1999). "The cortisol response to awakening in relation to different challenge tests and a 12-hour cortisol rhythm". Life Sci. 64 (18): 1653–60. doi:10.1016/s0024-3205(99)00103-4. PMID 10328525
• Wright CE, Steptoe A (2005). "Subjective socioeconomic position, gender and cortisol responses to waking in an elderly population". Psychoneuroendocrinology. 30 (6): 582–90. doi:10.1016/j.psyneuen.2005.01.007. PMID 15808928. S2CID 36466495
• Ranjit N, Young EA, Kaplan GA (2005). "Material hardship alters the diurnal rhythm of salivary cortisol". Int J Epidemiol. 34 (5): 1138–43. doi:10.1093/ije/dyi120. PMID 15951357