Millennials are decades away from retirement, but they are losing sleep over whether they will have enough saved once they get there. Having enough money to retire was the No. 1 source of financial stress for millennials polled by Schwab Retirement Plan Services. In fact, it was cited as the top worry for the 1,000 401(k) plan investors who participated in the survey of different generations. Approximately a third of these individuals were millennials, and 38 percent of them deemed saving enough money to retire as a significant financial stressor.

http://www.cnbc.com/2016/08/10/student-loan-debt-isnt-the-only-thing-keeping-millennials-awake.html