I've been tracking my physical activity and sleep on a regular basis. Now, I can see if my caffeine intake has any impact on my sleep quality. The UP Coffee app by Jawbone is an interesting way to see how your caffeine consumption (coffee, tea, etc.) correlates with your sleep. You'll need to log your caffeine intake and wear your Jawbone UP while you sleep to tie all those data points together. I have almost 10 days of data, so let's see what I (a casual consumer of caffeine) will learn about myself.
Caffeine is also found in many sports drinks and energy gels, so make sure to read the fine print on the GU Energy to see if' you're consuming caffeine.