If you’ve wondered how people actually spend their money once they’re retired, a new study from the Michigan Retirement Research Center at the University of Michigan can help you out.

Americans who save for retirement throughout their working lives, the study found, often hold tight to those funds after they retire.

While couples’ retirement spending patterns keep their wealth relatively stable over time, the study found, that changes—as one might expect—once they start paying for such things as medical care, nursing homes and other end-of-life expenses.

Researchers looked at the spending patterns of more than 4,600 households over a 15-year period, using a subset of the Health and Retirement Study that collects data on the health and wealth of people over age 70.

Wealth included savings and retirement accounts, investments, and home equity.

They compared how couples in two different income groups spent their money. The average couple at the 20^th percentile has about $14,000 in postretirement income, and $70,000 in wealth at age 74; the 80^th percentile couple has more than $30,000 in income and $330,000 in wealth.

What the researchers found was that, as long as both spouses lived, wealth stayed pretty much the same regardless of income/wealth level. However, once one spouse died, patterns differed.

For the higher-income couples, during the year of the first spouse’s death, wealth fell by about $60,000, with the biggest chunks of money going toward medical and nursing home care.

But for the lower-income couples, while wealth also drops sharply if the husband is the first to die, it changes very little if the wife dies first.

Again, unsurprisingly, after the death of the second spouse, while higher-income couples have enough left to provide an estate for their heirs, the assets of lower-income couples have pretty well been depleted.

So why do people hang onto their money so strongly once they’ve actually managed to retire?

The researchers suggest that a “significant fraction of all assets held in retirement are used to self-insure against the risk of high medical and death expenses.”