Why Are Cold Symptoms More Noticeable in the Evening?

Why Are Cold Symptoms More Noticeable in the Evening

Do you know that? Do you ever get that feeling when you awaken in the morning and realize that you have truly overcome the obstacle? Today is significantly better than yesterday, one would say. But in the afternoon, the slump comes back again; suddenly, you sniffle and cough more and feel weak. Don’t imagine that; quite the opposite. It’s only natural that you feel this way,” says Michael Fischer, Head of the Institute of Physiology at Med-Uni Vienna. “The activity of the immune system varies greatly throughout the day,” he explains. This is related to the circadian rhythm, or, in simpler terms, our internal clock.

Changes in cortisol levels

The cortisol hormone plays a pivotal role in this context. Produced daily in the adrenal cortex, this performance-enhancing hormone has the capability to efficiently suppress virtually any immune function. As a result, Fischer explains, it has extensive use in medical applications.

The body’s natural production of cortisol follows a rhythm. Cortisol levels peak in the morning, potentially leading to the suppression of inflammation during the day and a dampening of infection symptoms. As cortisol levels decrease towards the evening, symptoms become more pronounced. This phenomenon is well-recognized in the medical field, particularly among asthma patients. Fischer notes instances where asthma sufferers frequently seek emergency care in the middle of the night. They may not feel the symptoms as strongly during the day, but at around 2 a.m., when cortisol levels are at their lowest, they require intervention.

In the case of a cold, the body endeavors to mitigate these pronounced fluctuations. Such variations can be taxing on the organism, and especially in the morning, when cortisol levels are high and symptoms are subdued, pathogens could proliferate somewhat unnoticed. “The fluctuations are not quite as pronounced when we are under the weather, according to studies. However, a certain rhythm persists,” remarks Fischer.

Nighttime Regeneration

Additionally, the body engages in intensive regeneration during the night, contributing to the heightened sense of well-being upon waking. “At night, the body doesn’t need to allocate energy to other activities and can fully concentrate on immune defense,” states Fischer.

In the morning, following this intense regeneration phase, the body tends to be more resistant to bacterial challenges. Insights from animal studies, as per Fischer, can be extrapolated to humans, with the human body exhibiting a time-of-day-dependent response.

Another critical aspect of the circadian rhythm is the role played by the gut flora, which generally acts as a protective shield. Fischer notes that the activity of bacteria within us changes throughout the day. This is linked to the availability of food. During the day, when we consume food, the microorganisms that efficiently break down and utilize this food tend to proliferate. At night, however, a different type of bacteria, which doesn’t require external food and instead feeds on parts of our mucous membranes, becomes more prevalent. “Furthermore, disease-causing agents continually evolve. They attempt to exploit these daily cycles of our body to their advantage,” explains the physiologist.

Two Pillows, Not Just One

Our immune system works intensively to combat pathogens. During the day, defense mechanisms are active, keeping pathogens in check. In the evening, as energy reserves decline, pathogens multiply again. This leads to an intensified immune response, resulting in a higher evening fever, more pronounced headaches, or the return of a runny nose.

Evening discomfort, such as a congested nose or a phlegmy throat, is attributed to postnasal drip. This refers to the mucus that accumulates in the throat or nasal sinuses when lying down. During the day, movement or standing helps distribute the mucus, allowing it to drain due to gravity. At night, there’s a constant sensation of needing to cough to clear the airways. A slightly elevated head position, with, for example, two pillows instead of one, can be beneficial.