Blog
Sudden temperature changes: what they may do to your nose, heart and head
Sudden temperature changes are linked to runny noses, colds and death statistics, but the direction of the change matters. What each study measured and what nobody knows yet.
Seasonal diseases: why infections have a calendar and why it differs by country
Seasonal diseases are not only flu: a review of 60+ infections found eight drivers of seasonality. Examples from cholera to dengue, why one disease has different seasons in different places.
Flu season: when it starts in different countries, and why
Flu season in the US runs fall to winter and peaks between December and February. How it differs in the Southern Hemisphere and the tropics, and what four sources can and cannot say.
Excess winter deaths are higher in milder-winter countries: what the data show
Excess winter deaths in Europe are not highest where winters are coldest. What six studies found about cold homes, heating and mortality, and why none of them proves a cause.
Why we get sick more in winter: cold, dry air, and indoor time
What research says about why respiratory infections rise in the cold season: dry air, a cooler nose, crowded indoor days, and which findings come only from animals and cells.
What affects immunity: what research shows and what is marketing
What affects immunity, according to the studies: sleep, stress, social ties, age, vitamin C and echinacea, and why "boost your immunity" is the wrong frame. Evidence and limits for each.
Sleep and catching a cold: what the virus-challenge studies show
Healthy volunteers were given a cold virus on purpose; those who had slept less beforehand fell ill more often. What the studies measured, how uncertain the numbers are, what they did not test.
Fatigue and getting sick: cause, or the first symptom?
Does being worn out make a cold more likely, or is the tiredness already the infection starting? What virus-challenge studies and wearable data show, and why looking back rarely settles it.