All Day Energy!

By Joseph V. Amodio, Paige Greenfield, and Elizabeth Somer, R.D.
Feel like your energy level has more dips than the prepared-food section at Trader Joe's?

Here's why: One minute you're blasting through your to do list, and the next, you can hardly doodle a checkmark. Sound familiar? It should—it's Biology 101. Every day, you experience dips and surges in vigor, compliments of circadian rhythms. "They're the biological clocks in the brain, governed by the 24-hour cycle of light and darkness," says Martin Moore-Ede, M.D., Ph.D., CEO of Circadian Technologies, a research and consulting firm. These cycles control everything from hormone changes and temperature to blood pressure and your ability to think clearly. Take a closer look at your daily energy fluctuations, then read on to find out how you can skip the lows and ride the highs.

6:30 a.m. to 7:00 a.m. Sleep Inertia 
During the first 30 minutes you're awake, thinking and reaction times are substantially impaired. Levels of the hormone cortisol, which kicks in when you're stressed, are lowest around midnight and build up from there. This boost clears the cobwebs, and grogginess subsides.

7:00 a.m. to 12:00 p.m. Morning Hustle 
Between breakfast and lunch, your sense of alertness peaks. "Brain chemicals like norepinephrine, glutamate, and dopamine rise in the morning to promote awakeness," says Chris Fahey, Ph.D., a physician at Northwestern University's Circadian Rhythms and Sleep Research Lab in Chicago. Take advantage and tackle tasks that require critical thinking, such as closing a deal. Save routine activities like filing paperwork and Googling your ex for the slump to follow.

12:00 p.m. to 5:00 p.m. Siesta Period 
The Spanish weren't just onto something with sangria and paella; naptime demands an "Olé!" too. At some point during the afternoon, you could experience more drag than a Key West Halloween party—typically a spell that lasts up to 2 hours. According to Fahey, this urge to nod off may be an evolutionary trait passed down from our ancestors: Getting out of the sun and into the shade prevented heat stroke during the hottest hours of the day.

5:00 p.m. to 8:00 p.m. Sunset Spike
Wahoo! This is your biggest energy peak since the A.M. "There's a surge of energy and alertness when we come to the early evening," Dr. Moore-Ede says. It's also the trickiest time to nap, no matter how hard you try.

8:00 p.m. to 6:30 a.m. Transition Time 
Approaching sleep, we go through 90-minute cycles of feeling alert and drowsy, alert and drowsy. (It's no coincidence that sleep cycles follow the same schedule.) Dips and surges that occur before bed help your body transition from being awake to falling asleep, Dr. Moore-Ede says. Chemicals like melatonin flood your body as you snooze.

The Cortisol Connection
Here's the conventional rap on cortisol, the so-called stress hormone: Your body is like a slingshot that flings the stuff out whenever you feel threatened. But since our fight-or-flight hardwiring can't tell the difference between a real threat (saber-toothed tiger) and one that just seems like it'll kill you (your 70-hour work week), long-lasting stress keeps your body churning it out. Too much cortisol has been linked to weight gain, depression, and high blood pressure. Nobody likes that.

But recent research shows that, ironically, unrelenting stress can cause the slingshot to poop out, leaving you with too little of the hormone—and energy levels to match. Studies have linked low cortisol to chronic fatigue syndrome and fibromyalgia (a condition characterized by muscle pain and fatigue), though even healthy women can be affected. A study of 195 young women found that those with low morning cortisol levels were more likely to feel tired.

New research on cortisol supplements offers hope for healthy but sleepy women. When Mattie Tops, Ph.D., of the University of Leiden in the Netherlands, gave 27 Dutch women a 35-­milligram cortisol supplement—the average amount a healthy person produces every day--they had more vigor than when they took a placebo. Supplements probably aren't the answer just yet, though. "Cortisol inhibits the immune system," Tops says, "so you really have to know if low cortisol is to blame."

Water Works
What's the easiest, cheapest, and fastest cure when you're dragging? Water. Fatigue is, after all, one of the first signs of dehydration. Even a small drop in your body's water levels can hurt you. A recent study from Tufts University found that mild dehydration—a loss of just 1 to 2 percent of body weight as water—was enough to impair thinking. If it turns into full-blown dehydration, it could cause an imbalance in electrolytes like sodium and potassium, which aid muscles and heart function. How much H2O you need depends on your activity level (1 to 1 1/2 cups every 15 minutes while working out) and where you live (you lose more fluids in heat and humidity and at high altitudes). The National Academy of Sciences suggests that women consume 11 cups of fluid every day—though not all of this has to be water. About 8 cups can come from other drinks (including coffee and tea; caffeine isn't dehydrating as was once thought) and the rest from what you eat. Watermelon, cucumbers, and most other fruits and vegetables are obvious sources (1 1/2 cups of watermelon has almost a full cup of water), but lots of foods are wetter than you might have guessed. Oatmeal and beans, even a turkey sandwich, have at least half a cup. 
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