Researchers have known for some time that Sleep Apnea is associated with heart problems, although they weren't exactly sure why. Now they may have an important piece of the puzzle.

To keep his heart healthy, Tom Fontana tries to stay active.

But no matter how much exercise he gets during the day, it may be at night that his heart is most vulnerable.

Tom's wife has complained about his snoring for years, but lately it got worse.

"In the last oh, six to 12 months, she noticed that I had changes in my breathing pattern. I even stopped breathing at times while I was sleeping," Fontana said

Tom has Sleep Apnea and as a result has to sleep with a C-PAP machine.

Before he got one, there were times during the night that Tom simply stopped breathing.

"It lasts about, anywhere from 30 to 60 seconds on average but you can imagine, if you do not get air, that the oxygen in the blood will go down," said Dr. Ulysses Magalang of Ohio State University Medical Center

When oxygen levels drop during sleep --new research shows -- this affects the fat cells in our body.

That's important because fat cells release a substance that's been shown in the lab to control our blood sugar and even prevent hardening of the arteries.

But without enough oxygen -- that substance is not as effective -- and the heart can pay the price.

The good news is that the C-PAP machines that are already being used to help patients sleep better may be helping their hearts too.

"We have some preliminary evidence in patients that some of this substance, if you treat them with C-Pap, after three months, the substance goes up," said Dr. Magalang.

That may offer protection to the heart during a time when sleep apnea patients need it the most.

With a report by CTV British Columbia's Dr. Rhonda Low.