Der schlaue Fragen Thread

Mosquito bites itch because the mosquito saliva sensitizes your immune system and the allergic inflammation to it continues for a week or two after the bump first appears.

Normal cortisol production follows a diurnal cycle. Levels peak in the early morning hours (6 am–8 am) and decline throughout the day with a second, lower peak in the late afternoon (4 pm–6 pm).
Production of corticosteroids by your body follows a 24 hour cycle. Around 4 am your body starts pumping out more corticosteroids (to help you with the stress of getting up) and by 8 am your corticosteroid level is pretty high. At this time, mosquito bites or even poison Ivy won't itch very much. However, by 4 pm your corticosteroid levels will have gone down enough to release the allergic inflammation from being inhibited by the steroids. The corticosteroid levels will continue to drop and by 8 - 10 pm the itching will be most intolerable.
The circadian rhythm of cortisol levels influences your feeling of well-being, the levels of white blood cells in your blood and any inflammatory conditions you are suffering from. This cycle can be influenced by your patterns of sleep and your exposure to sunlight and darkness.

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