Sure, getting enough sleep is the biggest way to beat the 4:00 yawning session (I swear, there is something about this time--weirdly, I could fall asleep at 4 p.m. everyday!), but did you know that several other surprising things could be making you sleepy? Here are some unlikely yawn-inducers... WebMD recently ran a piece about the most common reasons for feeling tired. Here are some: 1. A hidden UTI: In some cases, fatigue may be the only sign of a urinary tract infection, reports WebMD. If you suspect something's up (and you have pain and burning when you pee) talk to your doc. A urine test can quickly confirm a UTI. 2. Your diet: If you're not eating enough, you will be tired. Calories = energy, my friends. (I feel like I sounded just like John McCain when I wrote that.) 3. Food allergies you didn't know you had: Some doctors believe that exhaustion could be a sign of hidden food allergies. 4. Caffeine overload: You probably reach for more coffee when you're tired, but experts say that too much caffeine can sometimes backfire, causing you to feel more fatigued. Maybe skip the triple-venti today. 5. Undetected thyroid problems: Fatigue is one symptom of a thyroid condition called hypothyroidism. Fortunately, this is such a treatable thing (I have it, and just pop a pill each day--no biggie). Most health experts concur that every woman should have her thyroid levels tested every few years (just a simple blood test) to rule out any such conditions (they're common in women).