Caffeine has a half-life of about 4 hours (if I remember correctly), so at least a few hours. And are you sure you had 700mg? Because that’s a lot. That’s roughly the equivalent of 7 cups of coffee, so unless you have a very good tolerance, you should be feely pretty jittery for a while.

Anywhere from 30min – 8+ hrs

Depending on a lot of different things

I can drink a pot of coffee on my off mornings, and it has me up all day. Seriously it is like crack to me. I won’t eat, I won’t drink, I have to use the toilet too many times to count. 700mg is a huge amount of caffiene. Most energy supplements containing caffiene only have 100–200mg in them!

I would say that would be highly dependent on the person. I, for example am not effected by caffeine at all, where others I know can drink a single cup of coffee and be bouncing off the walls for hours.

Wear off? Meaning you won’t feel so awake and maybe hyped up? Or, when might you start feeling withdrawal? If you have caffeine every day that will make yourtolerance much higher, so once you get down to your normal level of caffeine in your body you will feel it has worn off. So if 4 hours is the correct half life, I am not sure if itis, and you drank twice as much cafeine as you usually do, you will feel normal, normal for you in about 4 hours. If you usually don’t drink caffeine at all, it will take longer. If you are asking when the headache might start, and maybe you will feel crappy, almost under the weather, that usually takes around 15+ hours. Unless you have more caffeine before you ever get to the point of any withdrawal.

Depends on the person. One single mug of reg coffee and my sleep is drastically affected . Other people can drink a couple cups after their evening meal and drift right off . LOL !!