The report found that as well as being associated with increased risk of cardiovascular disease, depression, diabetes, hypertension and overall mortality, a lack of sleep also “impairs our basic social conscience”, which makes us less likely to want to help other people.

This conclusion was based on a number of research methods, including looking at how people’s behaviour changed after daylight saving hours were implemented, when most people lose an hour of sleep and many people’s circadian rhythms are disrupted by the changes in daylight. According to the study, charitable giving decreased by 10% in the week after daylight saving hours were implemented in certain states in the US. That same drop wasn’t seen when people gained an hour as clocks changed in the autumn, nor in states that do not change their clocks.

Sleep and mental health: the scientific reason you feel selfish when you’re tired