Use Sleep as a Nightly Immune Reset Window
During sleep, a specific migration happens that most people have never heard of: a large portion of your circulating immune cells pull back into the bone marrow, while neutrophils emerge and begin depositing collagen and clearing biological debris throughout the body. Krummel describes this as a cleanup phase the system cannot run while you are awake and generating more metabolic byproducts. The reparative processes that happen overnight, including clearing cellular debris, resetting tissue-resident immune cells, and allowing lymph to drain, require a quiet period where the body is not producing new damage faster than it can be cleared. The lymphatic evidence alone is visible without any lab equipment. The fluid pooling under your eyes when you are sleep-deprived is literal lymph accumulation, and it clears within one to two nights of adequate sleep. Krummel points to macrophages in the eye that clear the lens overnight as one example of how specific and localized these cleanup processes are. The analogy he uses: you can only clean a windshield when the car is stopped. You will never get ahead of the grime while driving through rain. The immune system runs the same logic. One lousy night of sleep is often enough to tip you into susceptibility to whatever is circulating in your environment, while being well-rested produces a subjective robustness that reflects an actual biological state change.