Sometimes nature presents scientific questions that are more unpleasant than pleasant to investigate. Mine currently have to do with chigger-bites.

The sources I've read say that chiggers are larva that create feeding tubes in the skin and then secrete enzymes that cause the skin to liquify into a form consumable for the chiggers. After gorging themselves the chiggers apparently fall of to become harmless vegetarian mature insects (or maybe they have 8-legs, I forget).

The noticeable skin reaction only begins after the chiggers have gone, according to some sources. The swelling, itch, and general irritation are supposedly the product of the plastic-like tubes formed in the skin, which take several days or weeks to break down. This seems to be confirmed by the experience of greater irritation when pressure is put on the skin, such as by wearing socks and shoes.

What I am wondering is why it would be that these wounds would become more irritated and inflamed at night. If there were still live animals living in the skin it might make sense that they become more active at night, as are other parasites. But since I'm tentatively invested in the idea that the welts only appear after the animals have left, this seems not to be the cause.

The best hypothesis I can come up with is that during waking hours, the vascular muscles of the feet constrict to avoid swelling and releasing too much body heat. As a result of reduced blood flow, less histamine and other blood liquids and solids are available to the skin for reacting to the bites/tubes. When laying down and relaxed, the blood vessels may relax to allow replenishment of nutrients to the cells and repair. As a result, the hystamine effects (itching) and swelling of the welts would increase.

Is this a plausible explanation or can someone debunk it? Skepticism appreciated and sought.