By now, you should know that it's ideal to close your peepers and rest for 15 to 20 minutes when your body slows down in the afternoon. But what if a nap at work just isn't an option? The next best strategy is to walk yourself through activities that send "Pay attention!" signals to your brain. These don't have to be time consuming, and they don't take any extra equipment that will clutter your space.

1. Use your non-dominant hand.

Although brain development is highly individual, scientists associate the right side of the brain with creativity, perception and empathy, while they associate the left with language, judgment and intellect. With this in mind, the left side of the brain controls the right hand, and the right side of the brain controls the left. By using your non-dominant hand, you force the hemisphere you don't normally use to spring into action. For a twist, try drawing or writing double using both hands at the same time. In the long term, this exercise can integrate the hemispheres for improved intellect, creativity and even open-mindedness, according to researchers.

2. Flip stuff.

Part of your brain's job is to constantly interpret visual and physical cues, such as force, to figure out where you are in space. This sense is known as proprioception. When you flip objects such as pictures or books upside down, your brain goes into "alert mode", trying to figure out what's going on. According to Dr. Stephen Brewer, medical director at Canyon Ranch in Tucson, Arizona, that will help you pick up details you might otherwise tune out.

3. Look at something adorable.

Finally! An excuse to look at cute cat/dog videos and pictures at work! According to researchers from Hiroshima University of Japan, checking out pictures of cute animals upped performance on concentration tasks. The researchers theorize that the results connect to the natural, evolutionary instinct people have to protect babies. The brain becomes more attentive to perceive potential threats to young and detect their immediate needs.

4. Work with lists (with constraints)

It probably doesn't take you much mental energy to count to 100. But what about backward? Can you do it in x seconds? How about backward by 7s, 5s or 3s? Can you go through the alphabet while finding a noun for every letter? What about creating a numbered list of objects that fit a specific category? These list exercises all force your brain to use multiple types of data (e.g., language, color, shape) at once, thereby getting more regions of the brain working together. You also have to focus more due to the unusual application, sequencing or pairing of the information, keeping track of where you are in the task.

5. Read something as fast as you can.

In a study led by Princeton University psychologist Emily Pronin, participants read a series of statements at different speeds (twice as slow as normal, normal and twice as fast as normal). When participants completed a questionnaire afterward, they reported feeling more energetic, creative and powerful, even though some of the content contained depressing statements. The researchers concluded that the speed at which people cognitively processed was just as important as the content they processed in terms of affecting mood, and that trying to complete thought sequences faster can give you both an emotional and physical pick-me-up.

6. Put on some quick music.

Research from New York University, Roanoke College and the University of Wisconsin-Madison reveals that brain waves actually synchronize to the tempo of music (and other sounds) around you. In other words, you can use music to coax your brain into a more active state. This energizes you by itself, but if you want, take it one step further by tapping out rhythms of specific instruments (try one in each hand!), free-association drawing what you think of from the melody or lyrics or listening for specific information, such as the number of pronouns or color words.

There's nothing wrong with you if you start to feel a little mentally fuzzy around 3:00 p.m., but there are plenty of ways to get out of the fog and back to productivity. Use whichever of these tips are appropriate for your workspace, and don't be afraid to pair them with other stay-awake strategies like grabbing a walk or chatting with a buddy!