Because allergic symptoms are caused by your immune system responding to a foreign substance, any changes in your immune system can lead to changes in the severity of your symptoms.

At nighttime, our internal body clock – also known as our circadian rhythm – causes our immune system to become more active, therefore triggering an increase in allergy symptoms.

“This happens because cortisol, an anti-inflammatory hormone that helps to manage the body’s response to allergens, tends to be at its lowest levels during the evening and night,” Kirsten explains. “This decrease in cortisol can lead to an increase in inflammation and a heightened allergic response, resulting in more pronounced symptoms.”

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