It’s a common frustration: your cold symptoms feel manageable during the day, but as soon as evening arrives, the coughing, congestion, and overall discomfort intensify. You’re not imagining it. There are genuine biological reasons why colds often feel worse at night. This phenomenon is primarily linked to your body’s natural circadian rhythm, hormone fluctuations, and even gravity.
The Circadian Rhythm and Immune Response
Your body operates on a roughly 24-hour cycle known as the circadian rhythm, or internal clock. This rhythm influences various bodily functions, including your immune system. At night, your immune cells become more active. When these cells detect cold viruses, they initiate an inflammatory response to fight off the infection. This increased inflammation can exacerbate respiratory symptoms like nasal congestion and coughing, making you feel more unwell as nighttime approaches.
Woman in bed with cold experiencing nighttime symptoms, tissues and cold medicine on nightstand.
Cortisol Levels and Inflammation
Hormones also play a significant role in the fluctuation of cold symptoms throughout the day. Cortisol, a hormone that regulates stress responses and also has anti-inflammatory effects, naturally rises in the morning. This rise in cortisol helps to suppress inflammation, which can lead to a temporary reduction in cold symptoms during the daytime. However, cortisol levels decrease at night, diminishing its anti-inflammatory effect. As a result, the inflammatory response to the cold virus becomes more pronounced, contributing to the worsening of symptoms like congestion and cough as the day ends.
The Effect of Lying Down
Finally, the simple act of lying down to sleep can also intensify cold symptoms. When you are upright, gravity assists in draining mucus from your nasal passages. However, when you lie down, this mucus can pool in the back of your throat and nasal passages. This pooling effect can worsen congestion, trigger coughing, and make it more difficult to breathe comfortably, further contributing to the feeling that your cold is much worse at night.
While it’s frustrating to experience intensified cold symptoms at night, understanding these underlying reasons can be helpful. Typically, cold symptoms, including coughs, will improve within a week. If your cough persists for longer than three weeks, it’s advisable to consult a healthcare professional to rule out any other contributing factors.
