Nearly three-fourths of adults in the United States don’t get enough sleep, and they often compensate for their sleep losses by consuming caffeine. A recent study found that caffeine and sleep deprivation reduce brain gray matter volume.

The study involved 36 healthy adults who regularly consumed less than 450 milligrams of caffeine daily—about the amount in four or five cups of coffee. During five days of sleep restriction, 19 participants received 300 milligrams of caffeine in coffee, and 17 received decaffeinated coffee. Researchers analyzed changes in the participants' brains and performed PET scans to measure the availability of the A1 adenosine receptor—a protein involved in sleep regulation—and its relationship to brain plasticity.

They found that caffeine and sleep restriction synergistically affected brain regions involved in visual processing, decision-making, executive functions, and regulating sensory information, sleep, and consciousness. Participants who had decaffeinated coffee during sleep restriction had more gray matter than those who had caffeinated coffee. Participants with lower baseline adenosine receptor availability generally demonstrated greater gray matter losses.

These findings suggest an adaptive increase in gray matter volume occurs with sleep restriction, but caffeine impairs this adaptation. Caffeine may have beneficial effects on the body, however, such as boosting autophagy. Learn more in this Aliquot featuring Drs. Guido Kroemer, Satchin Panda, Elissa Epel, Matthew Walker, and Rhonda Patrick.