Stand by the office vending machine at 3:23 p.m., and you'll probably see a parade of co-workers slinking over to grab a chocolate bar.

That's because at precisely 3:23 p.m., the average person succumbs to his or her cravings, according to a recent Atkins Diet survey. While we like to think of ourselves as individuals with willpower and self-control, the truth is that our bodies tend to follow a general rhythm.

In fact, our bodies are very predictable when it comes to cravings, energy slumps, stress and other factors. But once you learn the time of day that you're more likely to down a venti latte or lose your temper, it's easy to beat the clock and correct your habit.

Learn how by following these tips.

5 a.m.

The problem: You're exhausted

The science: At 5 a.m., the roads are at their most dangerous due to fatigue-related traffic accidents, said Andrew Moore-Ede, publications director for Circadian, a Massachusetts-based consulting firm for shift workers.

Beat the clock: By 6 a.m., the sun rises and gives you a natural energy boost, Moore-Ede said. So if you can wait the extra hour before heading to work, you should. If you can't, use the common truck-driver trick: Drink one cup of coffee and then take a 15-minute nap. It takes approximately 15 minutes for the caffeine to be absorbed into your blood, and 15 minutes is the perfect amount of time to take a power nap because you'll be waking up in your light sleep stage and won't feel groggy. Don't have time for a nap? Roll down the windows or blast the air conditioner, or chew on some ice, Moore-Ede said. If you have a choice, try driving or doing anything requiring your brain at 6 p.m., when your energy peaks. Not so coincidentally, that's the time when the most athletic world records have been set, Moore-Ede said.

11:45 a.m.

The problem: You're stressed out

The science: A poll of 3,000 adults by the health supplement Bimuno finds that at 11:45 a.m., you're most likely to realize exactly how much work you have left to do before you leave for the day. The feeling is worst on Tuesdays, when you also come to the conclusion that you wasted Monday away on Facebook and now you've got a billion things to do before Friday.

Beat the clock: The average American spends two hours every day at work wasting time, according to a new survey by America Online and Salary.com. The biggest distraction that affected 45 percent of people was the Internet. There's a simple solution, said Mark Strong, owner of Mark Strong Coaching, a life and career coaching company in New York.

"The human brain is not wired to do more than one thing at a time. You can dramatically increase productivity by turning off your phone and shutting your door when you're answering email," Strong said. "Or, try shutting off your phone and monitor when you're meeting with someone. Most people fight this, but when you try it, it's incredible how much more you can accomplish."

If you find yourself logging into Facebook first thing in the morning — and then wondering where the time went two hours later — try using social media or other personal websites as a reward for finishing your work (or even segments of your work), Strong said. Set a timer for 15 minutes to make sure you don't spend too long on nonwork pursuits.

Noon

The problem: You're at the gym

The science: A 2008 study by researchers at Long Island Jewish Medical Center in New York found that midday — or, more specifically, noon — is the worst time for your body to exercise. Your lungs follow the same circadian rhythm as the rest of your body, and the time of day when your lung performance tanks is at noon. The amount of air that you can exhale in 1 second at noon is more than 15 percent less than the amount you can exhale at 4 p.m., said Dr. Boris Medarov, lead author of the study and co-director of the Sleep Disorders Center at the University of Southern California.

Beat the clock: Your lung performance peaks between 4 and 5 p.m., which makes it the best time to do aerobic exercises. But if the only chance you can get to the gym is at noon, you should still go, Medarov said.

"I would use common sense. Exercise when your body is telling you it's the best time, emphasize proper techniques and types of exercises as well as consistency rather than the time of day selected for activity," he said.

2:16 p.m.

The problem: You desperately need a cup of java

The science: A study by Typhoo tea finds that every day at 2:16 — about two hours after lunch — you're going to hit your energy slump and head to your nearest 'Bucks. The biggest problem is that you may be in the middle of an important meeting and can't take a coffee run. The other issue is the caffeine, which stays in your system for eight hours. So if you're planning a 9 or 10 p.m. bedtime, your midday energy slump may interfere.

Beat the clock: An energy slump results from one of two things: Too many carbs at lunch, which leads to an onslaught of insulin and a subsequent drop in blood sugar, or eating too little at lunch, said Sophie Pachella, nutritionist and founder of EatStrong, a New York-based weight management and nutrition consulting company. To combat this, make sure your meal contains 6 to 8 ounces of lean protein (chicken, fish or tofu), healthy fats (nuts, avocado, olive oil) and complex carbs (whole grains, brown rice). If you still crash, try snacking on some peanut butter on celery or a handful of almonds.

3:23 p.m.

The problem: You're craving a candy bar

The science: At 3:23 p.m., dieters are most likely to give in to their cravings, according to an Atkins Diet survey of 1,250 dieters. Sixty-two percent of people broke their diets in the midafternoon, while 16 percent caved in the morning and 22 percent grabbed a guilty late-night snack.

Beat the clock: If you're not eating a lunch that's satisfying, you're going to have an unhealthy craving a few hours later, Pachella said. The key is to avoid having your blood sugar levels plummet, which will make you feel moody, irritable and in desperate need of a sugar kick. So make sure your lunch contains protein and healthy fats. A perfect lunch to eat to avoid a midday craving could include a turkey-avocado sandwich on a low-carb wrap or a salad with two servings of salmon, walnuts, avocado and an olive oil-based dressing. Stay away from fat-free salad dressings, which are loaded with sugar, Pachella said.

sunday@tribune.com