Q: I love being outside in the sunshine, but by the time I get home, I feel completely wiped. Is the sun secretly stealing my energy?

A: You're not imagining it. The sun really can wear you out! A lot of people feel drained after a day outdoors, and there are actually some pretty solid reasons why.

First, think about what your body's doing to keep you cool. When you're out in the heat, your internal AC -- sweating -- kicks into high gear. That cooling system takes energy, and when you're losing fluids faster than you're replacing them, even just a little dehydration can leave you feeling sluggish and foggy.

There's also the way sunlight plays with your body's internal clock. Bright light helps regulate your circadian rhythm, which is your body's natural wake-sleep cycle. So after a full day in the sun, your brain might start nudging you toward wind-down mode earlier than usual ... even if you're not ready for bed.

And remember that being outside usually means you're moving around more. Whether you're swimming, hiking, chasing kids or just walking around in the heat, it adds up. Your body is expending more energy than it might on a regular indoor day.

One more fun fact: UV exposure, even if you don't get sunburned, can trigger a mild immune response. Your body starts quietly repairing skin cells that have been affected by the sun, and that background work can contribute to that "hit by a truck" feeling when the day is done.

So if you're coming home from a sunny day feeling totally wiped, give yourself some grace. Try to stay hydrated while you're out, sneak in some breaks in the shade and wear light clothing and sunscreen to keep your body from working harder than it has to. And if you feel like you need to crash afterward? That's just your body doing its thing ... rest up.

-- Dr. Charles Tapley is a family medicine physician with CHI Memorial Family Practice Associates - North River and a member of the Chattanooga-Hamilton County Medical Society.