1. Your heart works harder than normal. Higher temps make your heart beat faster. Basically, it's working harder because it's pumping warm blood from your body's core out to the skin's surface, which helps cool you down.
2. Your allergies act up. Flowers, plants, and grasses that produce pollen bloom in the summer . . . and even people with mild allergies can end up sniffling, sneezing, and feeling like crap because of it.
3. You toss and turn all night. As the temperatures goes up, our sleep quality tends to go down. Most people sleep best when it's 65 to 66 degrees . . . and summer weather makes it more difficult to find that happy medium.
4. You'll get lots of mosquito bites. Summer is prime time for mosquitoes. They grow faster when the sun is out, and we tend to be outside more in the summer, which makes us a perfect target.