Till Roennenberg coined the phrase. He’s a professor of chronobiology in the Ludwig-Maximilian University.
Social jetlag promotes practically everything that’s bad in our bodies,” he says. It occurs when we go to bed later and wake up later at the weekend than on weekdays.
Ok. So what’s the big deal about that. Well, apparently it IS a very big deal. Chronic sleep deprivation has been linked to many of the same illnesses as social jetlag: type 2 diabetes, heart disease, obesity and depression. It has actually been declared a public health epidemic by the World Health Organization and the US Centers for Disease Control and Prevention. A study by the Rand Corporation calculated that inadequate sleep costs the UK £50bn a year – equivalent to 1.9% of GDP – due to decreased productivity and sickness. Sleep deprivation also takes its toll on our daily lives, affecting our vigilance, hand-eye coordination, memory, logical reasoning and emotional stability.
But – wait for it – just like those annoying TV ads – there is MORE! Social jetlag disrupts the length and quality of sleep. Which in turn is linked to poorer academic performance. It puts the internal clock out of synch. So hormones are affected. Exposure to light is erratic. Light exposure, it turns out, is a very important thing.
“Almost all the hormones in your body are on some sort of circadian rhythm and when you are shifting your sleep time, the entire system is not going to be working as efficiently as it should,” says Sierra Forbush, a research assistant at the University of Arizona College of Medicine. She recently presented data from a study of 984 adults that suggested that, for every hour of social jetlag a person experienced each week, there was an 11% increase in their likelihood of having cardiovascular disease. Social jetlag was also associated with worse mood and greater levels of sleepiness and fatigue.
Sleep well – and long enough