Osmond, her siblings, and her father were what scientists call natural short sleepers. Some people don’t sleep enough because they have insomnia, or work a night shift; they tend to struggle with exhaustion, cognitive impairment, and even long-term health issues, such as elevated rates of depression and a higher risk of heart attack. But short sleepers, who make up less than one per cent of the population, spend significantly less time snoozing without any apparent health consequences. “Growing up, we didn’t realize that there was anything different about us,” Osmond told me. Only in 2011 did she learn that she has a genetic variation linked to short sleep. Her sisters, who were tested in 2019, have variations in the same gene. Osmond, now seventy-seven, sleeps no more than four hours a night.