The damage caused by sleep deficit first dawned on Gozal, a pediatrician, about 20 years ago, while treating children with sleep apnea, in which breathing is rendered irregular (through physical obstruction or damage in the brain) and sleep is interrupted. After they had surgery to correct the problem, many children appeared transformed. Those labeled mentally challenged became stellar students, and friendships and personalities improved dramatically.

Over the years, researchers traced apnea to cognitive and psychiatric impairments, high cholesteroland atherosclerosis, high blood pressure, obesity, and type 2 diabetes, to name a few.

Eventually, Gozal realized the apnea findings were applicable to adults who were burning the candle at both ends, whether they had apnea or not. He and his colleagues traced perturbations in sleep to a surge of pro-inflammatory molecules — from dangerous cytokines to C-reactive protein — that did massive damage throughout the body. For example, in adipose tissue (body fat), these pro-inflammatory molecules set the stage for obesity and type 2 diabetes; in the cardiovascular system, heart disease; in the brain, neuronal loss.

Fortunately, it’s often possible to reverse the damage caused by sleep loss. A 2007 study published in the journal Circulation, for instance, followed 26 children with apnea who had the inflammatory precursors of cardiovascular disease. By curing the apnea, Gozal reversed the damage in all except six of the children, and that’s because those six had a genetic predisposition to the disease.

This led to a seminal finding: The pro-inflammatory state caused by sleeplessness makes those who are already at genetic risk for certain maladies far more vulnerable to triggering them into an active disease state.

Gozal explains, for example: “If you are born with a familial predisposition to Alzheimer’s at age 70, a sleep disturbance could bring it on at an earlier age, say 55.”