To ensure vaccines work properly, men should get a good night’s sleep

Vaccines get all the glory, but it is really the immune system that does the heavy lifting. Indeed, those with weak immune systems often benefit little from vaccines. Aware of this, researchers have long thought that people deprived of sleep also ought to benefit less from vaccines, as sleeping less is thought to reduce immune function. A new analysis reveals that this is clearly the case—though only in men.

The immune system is metabolically expensive for the body to operate. When resources run low, it cannot function as well as it might when well supported. This is why people who are profoundly cold for long periods of time tend to fall ill—their bodies are burning calories to stay warm that might otherwise have been used to fuel their defence.