Winter Nights, Lights, & Stroke Risk

For Europeans, the clocks went back this week. For N. Americans, it’s next week.

Specifically: on Sunday the 2nd of November, when the clocks hit 2am, they’ll move back to 1am.

• Pros: bonus hour of sleep that night, and one hour earlier sunrise time thereafter
• Cons: one hour earlier sunset time thereafter, compounding the fact that the nights are also getting longer each night because of normal seasonal variation

Whether you love it, hate it, or are indifferent, it’s what’s happening. So, what does it mean for our health?

Well, the bonus hour of sleep can only be a good thing!

The longer (darker) nights, however, not generally a great thing, famously:

‘Tis To Season To Be SAD-Savvy: Seasonal Affective Disorder & SAD Lamps

But watch out, because…

Researchers (Dr. Jacqueline Lane et al.) examined data from 88,905 people aged 40+, and found that exposure to bright light at night raises cardiovascular disease risk (including stroke) by up to 50% in adults over 40, while brighter daylight appears protective through healthier circadian rhythms.

How this was measured: those 88,905 participants (of which 57% female, average age 62) wore wrist sensors for a week to track day and night light exposure, then were followed for about eight years for new cases of heart disease (in its many forms).

What they found: those exposed to the brightest nights had higher risks of coronary artery disease, heart failure, atrial fibrillation, myocardial infarction, and stroke, even after adjusting for lifestyle, socioeconomic, and demographic factors.

In terms of sex, it’s noteworthy that women showed stronger associations for heart failure and coronary artery disease than men did.

Why this happens: the evidence suggests that disrupted circadian rhythms from light at night alter 24-hour blood pressure, hormone balance, and inflammation, while reduced melatonin secretion and poor sleep heighten vascular stress.

What they recommend:

❝Maintaining dark nights and spending time in bright natural daylight may be simple but effective ways to support heart health in middle-aged and older adults.❞

Read the paper in full: Light Exposure at Night and Cardiovascular Disease Incidence

Catch-22?

So, how are we supposed to manage our mood in the long winter nights without making use of night-time lighting?

Bearing in mind: How light can shift your mood and mental health

Well, one way is simply decide a cut-off time for bright/unfiltered lights. Say for example, at 9pm you might switch to low/filtered evening mood lighting, ready for a 10pm bedtime, say. Adjust according to your preferred bedtime, of course, but it is known that morning larks are, on the whole, healthier than night owls:

Early Bird Or Night Owl? Genes vs Environment

..and for how to actually shift that if your genes predispose you to being a night owl but you’d rather be a morning lark, then see:

Why Not To Be A Night Owl After 40 ← night owls face a higher risk of cognitive decline compared to morning people, as well as higher cardiovascular disease risk, including heart attack and stroke.

And, for that matter: 10 Tips for Better Sleep: Starting In The Morning

There are more things to managing mood than just sunlight, too: Managing Seasonal Affective Disorder (Beyond Sunlight!)

…which means that not everything depends on maximizing well-illuminated hours.

Want to learn more?

You might like this book that we reviewed a little while ago:

The Power of When: Discover Your Chronotype And Learn the Best Time to Eat Lunch, Ask for a Raise, Have Sex, Write a Novel, Take Your Meds, and More – by Dr. Michael Breus

Enjoy!