Napping at your desk would not be advised
Studies have found that one of the side effects of dehydration is fatigue. Grab a bottle of water before your next meeting and take a generous swig every time you feel sleepy.
If you need a quick boost, stop by the office coffee pot and pour yourself enough caffeine to get you over that afternoon slump. At the very least, your repeated trips to the restroom will keep you from falling asleep.
Take a Walk
A brisk walk will get your adrenaline pumping, releasing those endorphins that make you feel energized and alert. When you find yourself drifting off at your desk, a quick walk around the block can be just enough to get you back on track.
Your boss probably will be far more forgiving of you disappearing outside for a quick break than snoring at your desk. If the weather outside isn't ideal for walking, take a quick walk around the building or run up and down the stairs a couple of times.
Even if you can't take a walk, a few minutes outside can do wonders to wake up your brain. The sunlight reminds your body that it's daytime, kicking in natural process designed to keep you awake during the day and asleep during nighttime hours.
If weather permits, you can combine your outside activities with a little exercise for added benefits.
If you're stuck in a meeting when drowsiness sets in, many of the above methods will be out of the question. Try taking slow, deep breaths as quietly as you can manage. Your co-workers will have no idea what you're doing and your breathing exercises will help your body's oxygen levels, giving your sleepiness the kick in the backside that it needs.
Listen to Music
We all have that song that wakes us up and gets us moving. Find that song and play it through earbuds when you're feeling sleepy. If midday slumps are a normal occurrence, consider making a playlist that you can fall back on whenever you need some wake-up music.
If your office is private, feel free to dance around a little. The movement will provide the molt of adrenaline you need.
It's difficult to fall asleep while you're chewing on ice. The extreme cold will ignite your senses and you'll be too busy chewing to doze off. If your place of work has an ice machine or cafeteria, keep a cup on hand to fill up whenever you need a quick refresher.
Try a Snack
There are healthy snacks you can keep on hand that will battle the afternoon slump without relying on sugar or caffeine. Foods like roasted edamame, baked chips, and fruit are great for waking you up and they won't add to your waistline.