Children who grow up without a daily routine of set bedtimes and mealtimes do worse at school, a report suggests.
Research for the Prince's Trust suggests those with poor exam grades are twice as likely to claim their days lacked structure as they grew up.
The study of 2,136 16- to 25-year-olds found more than a quarter did not have a set bedtime while growing up.
Youngsters with poorer grades were also twice as likely to say they did not have regular mealtimes.
Some 14% of young people said they had grown up without set mealtimes, compared with 30% of those with poor exam grades.
The research also suggests that 27% of youngsters did not grow up with a set bedtime. This rose to 39% for those who left school with fewer than five good GCSEs.
The data comes from the charity's latest annual Youth Index, which looks at how young people feel about their lives across a range of areas from family life to physical health.
It also suggested those who felt they "lacked structure and direction" while growing up also appeared to be less content and confident than their peers.
One in three of those with lower qualifications (33%) said they "always" or "often" felt rejected, compared with about one in five young people (22%) overall.
Princes Trust chief executive Martina Milburn said: "The absence of structure and routine in a young life can have a devastating impact.
"Without the right support, directionless teenagers can become lost young adults - unconfident, underqualified and unemployed."