(Image: Thinkstock)

Money, or lack thereof, has typically been blamed for causing sleepless nights for Americans, but a recent survey by Bankrate.com, found that the main stressor for 41% of all age groups was relationships.

However, older millennials, ages 28 to 37, lost sleep over money, work and relationships more than any other group. For example, whereas 50% of all millennials lost sleep over relationships, only 36% of those older cited having the same issue.

Further, 43% of older millennials say that money causes some restless nights. A closer look shows 24% worry about credit card debt while 17% worry about paying the rent or mortgage. This is more than any other age group.

Overall, the most mentioned monetary stress points for all age groups in ranking order were retirement savings, credit card debt, health care costs, housing payments and educational costs.

Both older and younger millennials (age 18 to 27) alike cited work troubles as a stressor more often than older respondents. Also, 17% of millennials say they lose sleep due to educational costs, a rate three times higher than the older generations.

Saving for retirement turns the table a bit, with 25% of younger baby boomers (ages 54-63) and 22% Gen Xers stating it stresses them. About 20% of older baby boomers cited it as a stress factor.

The study found that, overall, 30% of Americans stressed over work, 28% over health and 14% over politics.

The Bankrate study was conducted online by GfK Custom Research North America of 1,000 people 18 or older.