What Happens When You Don’t Get Enough Sleep

Scientists peer inside the sleep-deprived mind and body

Credit: Lizzie Roberts/Getty Images

A lack of sleep is linked to an incredibly wide range of ailments, from heart disease and Type 2 diabetes to obesity, depression, poor cognitive function, and even Alzheimer’s disease.

Less is known about why exactly poor sleep is so detrimental to physical and mental health. But researchers are zeroing in on the reasons and mechanisms, ranging from blood vessels littered with fatty deposits to a buildup of cellular garbage in the brain.

People who sleep less than seven hours a night have 40 to 60% lower levels of three molecules that are thought to play a key role in blood vessel health, according to a new study published in the journal Experimental Physiology. The molecules, called microRNAs, suppress gene expression of proteins in cells and have previously been linked to inflammation and poor blood vessel health.

“They are like cellular brakes, so if beneficial microRNAs are lacking, that can have a big impact on the health of the cell,” says Christopher DeSouza, a professor of integrative physiology at the University of Colorado Boulder.

DeSouza’s study was small — just 24 men and women ages 44 to 62. And it relied on self-reporting, with the people in the study filling out questionnaires about their sleep habits. Self-reporting is known to be inaccurate, as people can over- or underestimate their own behaviors. But it’s not the first time the researchers observed poor health related to a lack of sleep. In a separate study, DeSouza and colleagues found discouraging health signs in men who sleep just six hours a night. The cells that line their blood vessels were dysfunctional, and their arteries didn’t dilate and constrict as well as men who sleep a longer amount of time.

The advice on naps is inconclusive, and federal sleep recommendations don’t even factor in napping after age 5.

In another, more robust study from earlier this year, a separate research team found that people who sleep less than six hours a night are at a 27% greater risk of having atherosclerosis, or clogged arteries, throughout their bodies, compared with people who get seven or eight hours…