This claim is true, people who get less sleep are more likely to die earlier. The study in the Guardian article found that consistently sleeping less than six hours a night increases the risk of premature death by 12% over 25 years compared to those who get six to eight hours of sleep. It also stated that having a lack of sleep has been linked to various health issues such as heart disease, high blood pressure, obesity, and diabetes. To back up this article's claims, I looked at a study done by Harvard's Division of Sleep Medicine. They also found that insufficient sleep impacts overall health, which can shorten lifespans. According to Harvard's findings, the impact of insufficient sleep isn't immediately obvious but builds over time, which can contribute to long-term health issues. These issues can go unnoticed for some time, causing unnoticed problems until it's too late.
https://sleep.hms.harvard.edu/education-training/public-education/sleep-and-health-education-program/sleep-health-education-86