A lack of sleep makes you feel old.

A study conducted by researchers at the Karolinska Institute in Sweden found that a lack of sleep can make individuals feel older than they actually are. The study surveyed 429 people between the ages of 18 and 70 to assess their subjective age and sleep patterns over the past 30 days. The results showed that each day of poor sleep added an average of 0.23 years to people's subjective age. In addition, further sleep restriction tests on 186 individuals revealed that those who restricted their sleep to 4 hours for two consecutive nights felt an average of 4.44 years older than their actual age. This study highlights the importance of sufficient sleep for maintaining a youthful subjective age. [Extracted from the article]