As a medical professional with a focus on immunology and respiratory health, I can provide some insights into why you might feel worse at night when you have a cold. The human body operates on a circadian rhythm, which is an internal clock that regulates various physiological processes, including the immune system's response to infections. Here are several factors that contribute to the intensification of cold symptoms during nighttime: 1. Cortisol Levels: Cortisol is a hormone that plays a crucial role in the body's stress response and has anti-inflammatory properties. It is typically higher during the day and drops at night. Lower cortisol levels can lead to increased inflammation, which may exacerbate cold symptoms. 2. Immune System Activity: The immune system is most active during the night, especially during the deep stages of sleep. This heightened activity can lead to a more robust response to the virus causing your cold, which can make you feel worse as your body fights off the infection. 3. Posture and Mucus Production: When you are lying down, mucus can accumulate in your nasal passages and throat, leading to increased congestion and difficulty breathing. This is why you might wake up with a stuffy nose or a cough that seems worse in the morning. 4. Sleep Disruption: Colds can disrupt your sleep patterns, leading to poor sleep quality. Lack of restorative sleep can weaken your immune system and make you feel more unwell. 5. Temperature and Humidity: The body's core temperature drops during sleep, and the air in your bedroom may be drier than during the day. This can cause the nasal passages to become more irritated and inflamed, worsening cold symptoms. 6. **Paradoxical Nocturnal Hemoglobinuria (PNH)**: While this is a rare condition, it's worth noting that some individuals with PNH experience worsened symptoms at night due to the body's circadian rhythm affecting red blood cell function. 7. Psychological Factors: The quiet and solitude of the night can make you more aware of your symptoms. When distractions are fewer, it's easier to focus on discomfort and illness. 8. Dehydration: During the day, you are more likely to drink fluids, which can help alleviate some cold symptoms. At night, reduced fluid intake can lead to dehydration, which can make symptoms like a sore throat and cough feel more severe. It's important to note that while these factors can contribute to feeling worse at night, they are not universally experienced by everyone. The severity and manifestation of cold symptoms can vary greatly from person to person. read more >>

At night, there is less cortisol in your blood. As a result, your white blood cells readily detect and fight infections in your body at this time, provoking the symptoms of the infection to surface, such as fever, congestion, chills, or sweating. Therefore, you feel sicker during the night.May 27, 2016read more >>