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How much caffeine works best for clarity of mind, while not disturbing sleep?

Say we score caffeine intake like this:

Green tea = 20 Black tea = 40 Coffee = 80

How much mg of caffeine do you take in daily and what works best to stay awake, while not disturbing your sleep?

Some also use supplements like L-Theanine to undo the side effects of caffeine, like anxiety. Do you use it?

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Varies a lot. My father used to drink a cup of coffee minutes before bed. If you've been drinking a lot, it has much less effect. If you haven't taken any caffeine in a month, a single cup late in the evening can keep you up the whole night. – Muz Aug 27 '13 at 7:49
Don't. It is a drug. And as every other drug it makes your nervous system over excited, and thus, gradually wearing it out. – akond Aug 27 '13 at 10:14

Unfortunately, this is one of those questions for which your mileage may vary greatly. Your weight, age, metabolism, activity level, liver health, all contribute to moving ceffeine through the body and can drastically affect its half-life from individual to individual.

This link goes into a great deal of detail about caffeine pharmacology and some of the factors involved.

My experience is this: I've been a HEAVY coffee drinker most of my life (think POTS per day instead of CUPS per day), though have recently switched to almost exclusively espresso. It's only been within the past year or so that I've started to find sleep issues if I ingest caffeine less than four hours before bedtime. Prior to that, I used to have a cup just before bed to relax me. Alas, no more. :)

My typical weekday routine is to have about five or six espressos in my first few hours of work. Lunch will generally include a double-shot or a large iced coffee during the summer. I generally don't have coffee in the afternoon...more because I'm not at my desk to pull a shot rather than lack of desire. I have a cup or two when I get home from work.

I find that I'm most productive in the morning, though afternoons are typically meetings, so I have a rough time gauging productivity or wakefulness in a context that is unproductive and mind-numbing. I find that wakefulness is more a function of sleep. If get my solid 6.5 hours, caffeine just helps me focus better and get more done. Bad sleep and ceffeine jsut keeps me from nodding off, with little no increase in attentiveness or productivity.

There are a lot of factors that go into your question, and it may require some experimentation to fall into your circadian rhythms, find your sweet-spot for sleep duration and caffeine intake. Studying your personal physiology and what works best for you is the ~real~ solution to this question, but I think understanding the broad strokes of caffeine pharmacology and then experimenting to see how that fits for you is an excellent first step.

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To avoid disturbing your sleep, you should avoid caffeine in the late afternoon. Caffeine has a half-life of 5 hours. The peak concentration will have subsided by that time, but you may still encounter trouble falling asleep.

The dosage of caffeine needed is dependent on how much tolerance you have towards caffeine. If one cup of coffee keeps you awake and motivated all morning long, that's all you need. Personally, I stick to about 100mg in the morning and 100mg after lunch, to keep me going through the work day.

If you don't normally drink much coffee, be meticulous with dwwilson66's personal approach. Going from zero cups a day to 5 or 6 may upset your stomach or give you undesired effects from the caffeine.

Here is a helpful wiki: Health Effects of Caffeine

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For me, it's around 2-3 cups of stiff espresso, perhaps around 170 mg x 2-3 = 340 - 510 mg. Anything beyond that will usually keep me awake slightly longer and in increasing amounts of time the more cups I drink. Regular drip-coffee is stronger than espresso, so perhaps 2 would be my limit before it would disturb my sleep.

Haven't tried L-Theanine or such.

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I've been experimenting with coffee to help with my attention and get rid of the evening slump. Just as a base-line I don't drink much coffee in general but I've started having a cup at 3PM (I've tried other time and this seems to work for me) followed but driving lots of water up to 5:30 PM when I leave work for the gym.

It works really well for me, I'm not as tired when in the evening and can actually do stuff. Not I do drink Tea but I don't drink much coffee up to this point.

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