Gloomy office got you feeling like taking a nap under your desk? There's a reason for that. "Research has found that regular exposure to natural light -- actual daylight -- maintains higher energy levels," says Phillips, who explains that environmental cues play a huge role in our body's energy cycles throughout the day.

But that doesn't mean you have to grab your laptop and sunglasses and head outdoors. On the contrary, Phillips says exposure frequency -- rather than duration -- is more important. So, instead of sunning yourself like a sleep-deprived lizard during lunchtime, try exposing yourself to five minutes of natural light every hour. Too busy to sneak outside eight times a day? Visit that water cooler by the window or touch base with the office hottie who has the office with a view. And if you're kind of big deal at the office (aka you can't step away from your desk ever), consider investing in a blue light like Philips Energy Light, $199.99, which emits rays that simulate natural light.

You've probably already heard that exercise can increase energy levels, but that doesn't mean that you have to carve out a half hour for a workout. (Because, let's be real, if you -- the reader of this energy-boosting tips article -- had 30 minutes to spare, you'd probably use 'em to catch up on precious sleep.)

When it comes to fatigue-fighting exercise, Phillips explains that frequency of exercise is more important than duration. Translation: A quick 10-minute exercise routine or even a brisk walk can be as effective as a gym class in getting you to perk up. "When you exercise, your heart beats more intensively and moves oxygen throughout your body," says Phillips. "You also tend to breath more deeply, which also helps oxygenate all of your cells -- all of which helps you feel more energized."

And speaking of breathing, you may think you have this whole inhale-exhale thing under control, seeing as, you know, you've done it all your life. But according to Phillips, "There's an art to breathing, and unless you're breathing well, you're not giving your lungs, your blood and your brain ideal amounts of oxygen to have energy."

But no need to hyperventilate, because Phillips has a quick breathing exercise you can do two to three times a day that will have you feeling like you got a full night's rest:

Exhale all the way through your mouth while making a whooshing sound.

Inhale slowly through your nose for five seconds and then hold your breath for a count of six.

Exhale slowly through your mouth for a count of seven, while making that same whooshing sound again.

Not only will this breathing exercise create increased, energy-boosting oxygen levels, but the more you practice it, the more it will help you unconsciously improve your everyday breathing.

If, like a lot of energy-zapped people, you have trouble falling asleep, you may reach for a daily glass of wine to help you unwind. But, according to Phillips, having more than one alcoholic drink a day -- particularly if you're a woman -- can make you feel more tired than if you had just stuck with water.

Not only does alcohol have a dehydrating effect, which makes you feel tired, but it drains your body of magnesium. "Even slightly low levels of magnesium can cause fatigue," says Phillips, who explains that your body excretes magnesium when it metabolizes alcohol.

And while alcohol might help you knock out quicker, it makes you sleep more fitfully, robbing you of precious REM, or deep, sleep -- so you wake up feeling even more exhausted.

When it comes to breakfast, not all meals are created equal. To get the most energy-boosting benefits from your morning meal, Phillips recommends kicking off your day with a combination of complex carbohydrates and protein.

Foods rich in complex carbohydrates -- think fruits, vegetables and whole grains -- contain sugars that are a "readily usable source of energy for our cells," says Phillips. Unlike simple sugars -- the kinds found in foods containing glucose, sucrose, fructose or any other ingredient ending in "ose" -- the sugars found in complex carbohydrates allow for a slow and steady rise in blood sugar and, in turn, energy. That means you won't get that crazy sugar high and inevitable crash that you might get with eating, say, a supersweet breakfast cereal.

And as for proteins, Phillips says they are "important in manufacturing adenosine triphosphate (ATP), which is what we use for energy."

Some easy breakfast options: peanut butter toast and an apple, Greek yogurt with berries and whole-grain granola or oatmeal with walnuts and raisins.