Why Short Sleepers Catch More Colds

This study did something few sleep studies can: it measured people's actual sleep with wrist actigraphy for a week, then deliberately exposed them to a standard dose of the virus that causes the common cold under quarantine conditions, confirming infection with nasal cultures rather than symptoms alone. People averaging six hours of sleep or less were about four times more likely to develop a biologically confirmed cold than those sleeping seven hours or more. Notably, this held after accounting for age, stress levels, smoking status and socioeconomic factors, sleep duration remained one of the strongest single predictors of who got sick.

With 164 participants recruited over several years and viral exposure standardised in a controlled setting, this is a genuinely rigorous design, though a laboratory rhinovirus challenge is still a somewhat artificial stand-in for everyday cold exposure. It also measured only sleep duration in the week before exposure, not longer-term sleep patterns. The core finding is nonetheless hard to dismiss: this wasn't self-reported sleep or self-reported illness, it was an objectively measured week of sleep predicting a laboratory-confirmed infection.