Even as our lifespans get longer, a new study by a dating website claims that the day you turn 28 may be the day you become old.
The poll also found that among the 10 most popular changes in behaviour showing that one is no longer young, is the stage of life when our career becomes more important than our sex life, Daily Mail reported.
Almost half of all respondents to the survey said 28 was the age they considered to be when we stop being "young" and finally grow up.
Dating site www.SeekingArrangement.com polled 1,000 male and female members to find out exactly when youth ends.
A total 37 percent of women and 39 percent of men nominated 28 as the key age when one is no longer young. The second most popular reply was 30, chosen by 27 percent of women and 24 percent of the men.
When respondents were asked to nominate the 10 most popular changes in behaviour showing you are no longer young, the most popular answer was when our career becomes more important than our sex life.
The second most popular change is when you prefer listening to Radio 2 rather than Radio 1. Another key pointer indicating a person is leaving youth behind is that when one has no idea what is the number one song in the charts.
Other changes included: "You want to buy a property rather than rent. You have no idea what is number 1 in the charts. You start looking for a husband/wife rather a boyfriend or girlfriend.
"You prefer Strictly Come Dancing to X Factor. You would rather go on holiday with a person you are in a relationship with than a group of friends.
"You would rather cook for yourself than rely on a ready meal or takeaway. You would rather live on your own than share a flat or house. You stop going to nightclubs."