Here is a summary of findings...
- The less a person slept, the more likely he or she was to develop a cold (there was a graded association between infection rate and average sleep duration).
- Participants who slept fewer than 7 hours were 2.94 times more likely to develop a cold than those who had 8 hours or more sleep.
- The more efficiently a person slept (more of the time in bed actually spent asleep), the less likely he or she was to develop a cold (i.e. there was also a graded association between sleep efficiency and rate of infection).
- Participants whose sleep efficiency feel below 92 per cent were 5.50 times more likely to develop a cold than those whose efficiency was 98 per cent or more.
- Feeling rested was not linked to rate of infection.
- These relationships could not be explained by the potential counfounders such as levels of virus-specific antibodies beforehand, demographics, the season of the year, body mass index, socioeconomic status, health behaviours, and psychological variables.