Does daylight saving time have effects on heart health?

AUSTIN, Texas - Daylight saving time is this weekend. 

Early Sunday, March 9, our clocks will spring forward one hour, meaning many people will lose an hour of sleep, and that can have a negative effect on your heart. 

Dr. Kevin Gallagher, a cardiologist with Heath Hospital of Austin and Austin Heart in Fredericksburg, joined FOX 7 Austin's Rebecca Thomas to discuss.

Local perspective:

REBECCA: Dr. Gallagher, the American Heart Association says studies show an uptick in heart attacks on the Monday after daylight saving time begins. And in strokes for two days afterward. What is the cardiac connection here? 

Dr. Kevin Gallagher: So Monday is also known to be a very stressful time and period just coming out of the weekend. The extra stress added in Monday has been shown to have increased cardiac stress. When you add a time change, you're disrupting your circadian rhythm. Your circadian rhythm, as your time clock is completely regulated by your sleep and wake cycles along with your sunlight exposure. So, when you change, this disrupts your circadian rhythm, which is one of your main regulators of your hormones, more specifically, your hormone cortisol. So when your time clock is shifted, suddenly your cortisol regulations are disrupted. This can lead to extra stress in your blood pressure and your heart rate and some data out of New Women Journal suggests in the two days following your stroke, the risk may be relatively higher, about 8%, and your cardiac risk may be a relative risk higher for cardiac events of about 20 to 24%.

REBECCA: Do you see other effects on the heart after daylight saving time, such as increases in atrial fibrillation or blood pressure? 

Dr. Kevin Gallagher: Cortisol has a big effect on heart rate and blood pressure, so there is definite dysregulation of your blood pressure for days leading after daylight savings. And there's been studies showing increased events of AFib Rachael fibrillation post time-shifting, like daylight saving.

REBECCA: For people who already have a sleep disorder, such as sleep apnea. Do they face any extra risks with the time change? 

Dr. Kevin Gallagher: Patients with sleep disorders in general already have a interfering circadian rhythm. So, when you add the extra stress in a time shift, that's going to add to more disrupted circadian rhythm, which again would increase stress and their overall cardiac risk. 

REBECCA: So what do you recommend people do to prepare for the time change? So it's not that sudden shock to the body and the heart. 

Dr. Kevin Gallagher: Basically you want to make it a gradual adjustment. So a few days before the time change You want to start shifting your sleep, so you go to sleep a little bit earlier, 10 or 15 minutes, and you can kind of build that up to make up for that full hour for, say, five, six, seven days prior to the event. And then when you wake up the next day, you want to maximize your sunlight exposure, which helps reset your own internal clock and kind of build back your normal circadian rhythm. 

REBECCA: All right. Some great advice there. Dr. Kevin Gallagher, cardiologist with Austin Heart. Thank you so much for sharing your time and expertise with us tonight.