When do most heart attacks occur -- and why?

It's something of a Christmas miracle that Santa isn't long dead from a heart attack. Increases in stress levels mean increases in heart attacks, and it's hard to find a more stressful time than the holidays. In the United States, there are greater than 50 percent more heart attacks in winter months than in summer months, and it's mostly about stress [source: MNT].

Stress is one of the most difficult heart-attack risk factors to eliminate from our lives. And for people with high blood pressure (hypertension), it's crucial to do so.

High blood pressure can damage arteries because the increased force of blood pumping through them pushes hard against artery walls. Damage to the artery walls encourages plaque to form there, leading to clogged arteries. It's not clear exactly why stress can lead to heart attacks in people with hypertension, but it's probably related to the release of adrenaline [source: WCN]. Stressful situations cause your brain to flood the body with adrenaline, the "stress hormone," which triggers a fight-or-flight response. It speeds up your heart rate. With the heart trying to pump more high-pressure blood in less time, it would make sense that the risk of heart damage would increase.

You can stop eating trans fats and start walking around more; but it's a bit trickier to tell your family members that they can't pack into your home for the holidays. Holiday-related stress makes November through the end of December, also known as Thanksgiving through New Year's, the most popular time of year for heart attacks.

It's not hard to see why. Stress makes us do some unhealthy things, like eat the rest of the pumpkin pie after everyone leaves or skip a morning walk because we're hungover from too much eggnog. Along those lines, stress increases heart-attack numbers in two related ways: by decreasing healthy behaviors and by increasing risky behaviors.

Between Thanksgiving and New Year's, people do more of the things that can lead to heart attacks, including eating more high-fat foods, just eating more in general, drinking more alcohol and smoking more cigarettes. At the same time, they cut back on some of the things that can help prevent heart attacks, like extra exercise.

Rushing off to finish holiday shopping or get the turkey in the oven can make some people forget to take their blood pressure medication. This is a particular problem in the morning hours, when most heart attacks happen [source: MNT]. Blood pressure tends to be highest in the morning. If medication is getting your heart past that morning surge, skipping it can have dire consequences come the a.m. hours, especially after a night of drinking, smoking and cheesecake.

The overall result is that we abandon the activities that could keep us healthy, just when we need them most. To avoid the increased risk of heart attack during the winter holidays, it's important to try to maintain some balance. Drink one glass of high-fat, high-alcohol eggnog instead of two. If you feel yourself getting overly stressed, skip that one holiday party you didn't want to go to anyway. Start your holiday shopping six months in advance so you can avoid the last minute panic and the adrenaline surge that could put your heart over the edge.

And just in case things do start to get crazy, by all means, pin a "take your meds" note on the turkey in the fridge.