Blood Sugar Swings? This ONE Trick Stops Them

If you’re working hard to control your blood sugar, you already know the truth – it’s exhausting.

You eat the right foods… take your meds… and your numbers still won’t stay in line.

And if you’re like a lot of folks with diabetes, you’ll end up with even more drugs to manage those annoying blood sugar swings.

But what if you could stop those swings for good without touching another medication?

A new study shows it’s possible – and all you have to do is something I’ve been recommending for years.

The best blood sugar drug on the market may not be a drug at all.

It’s sunlight.

You’ve heard me talk plenty of times before about the importance of a healthy circadian rhythm – your body’s natural sleep/wake cycle.

But your circadian rhythm also helps keep your blood sugar under control. And the best way to improve your circadian health is through sunlight.

In the Cell Metabolism study, researchers placed people with type 2 diabetes into two tightly controlled environments:

• One with natural daylight during working hours
• One with standard artificial indoor lighting

Everything else—meals, sleep timing, activity, and medications—was kept the same.

The results were striking.

When exposed to natural sunlight, patients spent far more of the day with their blood sugar in the normal range.

Importantly, average blood sugar didn’t change much. What changed was volatility. Blood sugar stayed steadier. Fewer spikes. Fewer crashes.

The study also found that daylight exposure shifted metabolism toward burning more fat and less sugar and increased evening melatonin levels—both signs of a better-aligned circadian rhythm.

Sun exposure and a healthy circadian rhythm really can be your secret weapons for stopping blood sugar swings and keeping your numbers stable. Here are two steps you can take right away.

Step 1: Get sun exposure in your eyes first thing every morning – no glasses or contact lenses. You don’t need to look directly into the sun. Just keep it in your peripheral vision. This helps set your circadian rhythm for the day.

Step 2: Avoid artificial “blue light” at night – the kind you get from cell phones, laptops, and televisions. Your body mistakes this light for sunlight, and suppresses your melatonin levels. So shut down devices 60-90 minutes before bed.

View Sources

Harmsen, J.-F., Habets, I., Biancolin, A. D., Lesniewska, A., Phillips, N. E., Metz, L., Sanchez-Avila, J., Kotte, M., Timmermans, M., Hashim, D. de Kam, S. S., Schaart, G., Jörgensen, J. A., Gemmink, A., Moonen-Kornips, E., Doligkeit, D., van de Weijer, T., Buitinga, M., Haans, F., De Lorenzo, R., Pallubinsky, H., Gordijn, M. C. M., Collet, T., Kramer, A., Schrauwen, P., & Dibner, C. (2025). Natural daylight during office hours improves glucose control and whole-body substrate metabolism. Cell Metabolism, 38(1). https://doi.org/10.1016/j.cmet.2025.11.006