What's the best time to exercise? If you answered, "Anytime I can drag my spandex-clad ass to the gym," it's not that you're wrong exactly, but your body does respond to exercise differently throughout the day. Given how hectic life can be, it makes sense to get the most out of every minute spent exercising. Here, experts help you find the best time to schedule your workout based on the benefits you're looking to achieve.

If you have a stressful meeting planned

Work out just before it. Thirty minutes of moderate-intensity exercise can lessen your body's physiological reaction to stress by boosting feel-good neurotransmitters such as dopamine. "It also encourages your brain to switch off its stress response," says J. Carson Smith, Ph.D., an assistant professor of kinesiology at the University of Maryland. "You'll feel the effects about 15 minutes after you finish your workout."

If you have trouble sleeping

Do the right exercise before bed. You may have heard that vigorous exercise before bed makes it harder to fall asleep, but according to a new report from the National Sleep Foundation, people who exercise at any time of day or night get better z's than couch potatoes. If you're a poor sleeper, a quick yoga session is best. Research shows 30 minutes can improve sleep quality and help you conk out faster. It's also safer than sleeping pills, which can sometimes leave you dangerously drowsy while driving the next morning, says Dr. Barbara Phillips, medical director of the sleep lab at the University of Kentucky.

If you want to prevent injury

Aim for the early evening. Prone to pulled muscles, soreness, sprained ankles (you get the idea)? Then wait until after work to exercise. Early in the day when your natural temperature is lower, "your body isn't necessarily ready to jump out of bed and perform, so you may be more vulnerable to strain and injury," says Michael Deschenes, Ph.D., professor and chair of the department of kinesiology and health sciences at the College of William & Mary in Williamsburg, Virginia. To avoid injury, exercise between 4 p.m. and 8 p.m., when core temp peaks.

If you want to drop pounds

Work out before breakfast. Maximize your body's flab-burning potential by hitting the gym first thing in the morning. People who ran on a treadmill before breakfast burned about 20 percent more fat compared with a group who ate breakfast first, according to a recent study published in the British Journal of Nutrition. "Your body taps into fat stores for fuel instead of carbohydrates from breakfast," explains study coauthor Javier Gonzalez, who studies exercise and metabolism.

If you want to tone up

Exercise after dinner. Because of the uptick in core body temps later in the day, exercise performance improves. Namely, muscle strength increases slightly, coordination is better, and your VO2 max (the amount of oxygen delivered to muscles) rises. Translation? "Your workout may feel a bit easier," says Deschenes. It's a small improvement, but one that may help you upgrade from 5-pound weights to 10-pound ones, resulting in more marked muscle tone.

If you want to avoid an allergy attack

Work out in the evening. Fall allergies are often caused by ragweed—and those pollen levels are at their highest between 4 a.m. and 10 a.m. That means the morning run you thought would be energizing might make you groggy and bring on allergy symptoms that continue throughout the day, says board-certified allergist and immunologist Dr. Sakina Bajowala, a fellow of the American Academy of Allergy, Asthma & Immunology. Two options: Move indoors or work out later, when pollen counts are lower.

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