00:00 Deliberate cold exposure for short durations is unlikely to cause illness, and there are immune-enhancing effects associated with this practice.

02:54 Deliberate cold exposure for short durations is unlikely to cause illness, but spending time in cold, dry environments can increase susceptibility to viral and bacterial infections.

05:59 Deliberate cold exposure does not directly cause colds or other infections, but spending time in cold, dry environments and mouth breathing in that air can increase the likelihood of getting sick, so it is not recommended for those who are already feeling unwell.

08:57 Repeated deliberate cold exposure over a period of six weeks, done three times per week, showed trends towards increases in immune system markers such as IL-6 and various immune cells and molecules, suggesting an increase in immune system function.

12:00 Deliberate cold exposure done repeatedly over time can increase immune system markers, such as immune cells and molecules, but the effects are not highly significant and it is difficult to determine how these trends translate to actual resistance to specific viruses or bacteria; however, the release of norepinephrine and epinephrine in response to cold exposure can have proimmune effects in the short term, but chronic elevation of these molecules can reduce the number and efficiency of immune cells.

14:55 Deliberate cold exposure and cyclic hyperventilation can both enhance immune system function through the release of epinephrine and norepinephrine, but excessive levels of these molecules can suppress the immune system, so it's important to find a balance and adjust cold exposure based on how you're feeling.

18:07 Deliberate cold exposure can have both positive and negative effects on the immune system, so it's important to find a balance and adjust based on how you're feeling, and nasal breathing can help prevent infections.

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