Next time you wake up in the middle of the night for a bathroom break, take a quick look out the window.

You might notice plenty of other bathroom lights on at the same time--because you're not the only one "going" at that hour.

In fact, researchers now say that more than 1 in 5 U.S. men--21 percent in all-- wake up at last twice a night to urinate, a condition known as nocturia.

And the older you are, the more likely you'll be one of them: While just 8 percent of men between 20 and 34 have the condition, it affects up to 56 percent of men at least 75 years old, according to the study in the Journal of Urology.

The researchers only looked at data on men, which might not surprise people who think of nocturia as a prostate-related condition.

But that's not always the case, and other studies have found that women suffer from it at roughly the same rate. And for men and women alike, it's not just a sleep-disrupting inconvenience--it could also be a serious warning from your body that something is amiss.

One study last year found that nocturia patients have double the risk of an early death. Another study found that each extra trip to the bathroom per night increased that death risk.

Nocturia can also be a sign of an undiagnosed condition, including diabetes or even heart problems, or a side effect of common meds.

Tell your doc about it, and he might try to get you on even more meds--often synthetic hormones with side effects that can be even more unpleasant than those nighttime interruptions.

Some studies have found that up to 70 percent of the people who try those meds quit within six months.

Instead, simple lifestyle changes can often have you sleeping better and longer than you have in years.

One study last year found that a little exercise, a little less time awake in bed, keeping warm at night, and drinking less (especially in the evening) led to significant improvement in just weeks.

And if your nighttime potty breaks are caused by an enlarged prostate, try saw palmetto.

One study found that it works for up to 73 percent of men--dramatically reducing the number of nighttime bathroom breaks, or even eliminating them altogether.

And if it can cut back on all that flushing, who knows--it might even shave a little off your water bill, too.