“Humans are the only species that deliberately deprive themselves of sleep for no apparent reason,” neuroscientist Matthew Walker told The Guardian in a fascinating piece about his new book Why We Sleep. And that sleep-deprivation is costing us enormously.

Walker, the director of the Center for Human Sleep Science at the University of California, Berkeley, told The Guardian’s Rachel Cooke that sleep-deprivation is a public health epidemic. Not getting the recommended 8-hours of shuteye a night has been linked to everything from Alzheimer’s disease and cancer to profound negative impacts on mental health. “No aspect of our biology is left unscathed by sleep deprivation. It sinks down into every possible nook and cranny,” he told Cooke. “And yet no one is doing anything about it.”

Why We Sleep outlines how our current sleep crisis is a particularly modern malady. Walker told Cooke that it’s a bigger problem today compared to 75 years ago partly because “we electrified the night,” adding that “light is a profound degrader of sleep.” (Even more reason to keep your phone out of the bedroom.) Secondly, “there is the issue of work: not only the porous borders between when you start and finish, but longer commute times, too. No one wants to give up time with their family or entertainment, so they give up sleep instead. And anxiety plays a part. We’re a lonelier more depressed society. Alcohol and caffeine are more widely available. All these are the enemies of sleep.”

Read the whole piece on The Guardian. And if you want to learn how to sleep better, read more here and here.