Most of us would happily avoid the nuisance of having a head cold. A new study published by Prather and colleagues in the journal Sleep this month has demonstrated that short sleep is associated with increased susceptibility to the common cold.
While recent research has highlighted that insufficient sleep is associated with susceptibility to infectious diseases, most research has investigated the impact of sleep on the immune system by partially or completing depriving people of sleep in the laboratory.
In 2012, Cohen and colleagues studied sleep in a community setting and demonstrated that short sleep duration and poor quality sleep predicted the development of a cold following viral exposure. They measured sleep by phoning people each day and asking them to recall their bed and rise times, and the number of minutes of sleep ‘lost’ during the sleep period due to difficulty sleeping or intentional periods of wakefulness. This method has its challenges because we know that people tend to overestimate the amount of sleep they get and underestimate wake time.
The study published this month overcomes this issue by measuring sleep objectively using wrist-worn activity monitors, as well as completion of a sleep diary. (Wrist-worn activity monitors use movement to determine sleep and wake. They are fairly reliable measures of sleep duration but less reliable measures of sleep fragmentation.)
164 people completed screening during the 2 months prior to being exposed to the common cold virus. This included screening for smoking status, physical activity, mood and stress, and 7 days of sleep monitoring. Quarantined in a hotel for six days, they were then exposed to nasal drops containing live virus and monitored for objective signs of illness and infection. They found that participants who got 6 hours or less sleep per night were 4 times more likely to develop the common cold, compared to those who got 7 hours or more of sleep. However, in their study, objectively measured sleep fragmentation, and self-reported sleep duration and fragmentation, were not significant independent predictors of cold susceptibility.
To most readers this probably appears to be conventional wisdom, but surprisingly, this is the first study to objectively show that short sleep increases the risk of developing a common cold. It is also of course yet another reminder that getting enough, good quality sleep is key to overall good health.