n. The turbulent, rebellious middle age of the baby boom generation.
Other Forms
Most baby boomers don't feel fully 'grown up' until they are into their 40s. When our parents turned 50, we thought they were old! But today, women and men I've interviewed routinely feel they are five to 10 years younger than the age on their birth certificates. Fifty is what 40 used to be; 60 is what 50 used to be. Middle age has already been pushed far into the 50s — in fact, if you listen to boomers, there is no more middle age. So what's next?

Welcome to Middlescence. It's adolescence the second time around.
—Gail Sheehy, “New passages,” U.S. News & World Report, June 09, 1995
Parents spend less time with their adolescents for reasons that are peculiar to this stage of parenting:

By the time their first child turns 11, they probably have other children to care for.

They're also probably hitting their peak working years when companies demand more time and energy from them.

They're probably going through their own identity crises — "middlescence" — that mirror adolescent changes, thus making communication uncomfortable.
—Laura Sessions Stepp, “Time Out For Teenagers,” The Washington Post, September 28, 1993
1965 (earliest)
The stage at which most children begin to go wrong with parents is "middlescence," that awkward age between youth and premature grave in which the parent undergoes alarming physical and emotional change,
—Russell Baker, “You and Your Middlescent Parent,” The New York Times, December 05, 1965