People can build up a tolerance to caffeine by saturating the receptors in the brain that are activated by caffeine. So, after month of daily ingestion, some people can drink 4-8 cups of coffee a day and not have any problems. In this case, it's especially true that your mileage may vary greatly.
I used to be a caffeine fiend. But, when I started having sleep problems, I had to completely quit caffeine, and it does help. I could drink 2-3 triple espresso's in an all-nighter and then sleep like a baby when I was in college. Now, I drink 1/2 a cup of coffee and I'm buzzed for hours, and I don't sleep well that night.
In this regard, I'd go with wikipedia. There are plenty of doctors who are wrong in the world--they are only human.
Thus the (informal) "half life" of one cup of coffee could be 4 hours, but two cups could be 8 hours, and so on.
(To the extent I can track the estimates of "3.5 to 6" or "5.7" hours of caffeine half-life back to original sources, it looks like the studies were done in 1978 and 1980. Maybe modern caffeine consumption has moved to a level where linear rather than exponential elimination dominates?)
Damn. I was hoping to calculate the optimal hour for a caffeine "booster" after the initial morning fix.
Looks like about 5 hours:
So, on average, your sleep specialists have about 13-15 years of schooling. It's about the same ammount of time that it would take to become a Plastic surgeon, or Interventional Cardiologist, Cardiothoracic Surgeon of Invasive Radiologist.
It's not a light weight course of study. Certainly not 4 hours worth.
Dr. Walsh in particular is a professor at the nearby St. Louis University. If you do a search on Medline for Dr. Walsh you will see that he is active and published with studies on sleep disorders.
http://www.stlukes-stl.com/services/sleep_medicine/research_...
If you were going to try it, go for a low dose. Try 300 micrograms [1]. Most stores sell a minimum dose of 1 milligram, but you can find the lower dose stuff on Amazon.
Source: My cousin... he's a nurse, so maybe take my advice with a grain of salt.
SwellJoe's comments on caffeine and sugar are true. My doctor told me that caffeine has about a 10-hour half-life. After noon it's generally something I avoid.
If you try these things (or at least a good portion of them) and you don't see any improvement it's time to start looking at health conditions rather than merely poor habits. Sleep apnea is a major cause of chronic exhaustion. Restless Leg Sydrome is another. With both of these you are constantly waking up during the night and never attain the deep sleep needed to rest.
My father had sleep apnea - when he did an overnight EEG sleep study the doctors determined that he was waking up over 80 times an hour due to airway blockage. He started using a CPAP about two years ago. The CPAP is a face mask which generates positive air pressure to keep airways open. The difference was dramatic. He's much more energetic, much less grumpy, and has in general been much happier since he started using it.
I personally had awful sleep for years. I was perpetually exhausted. The only way I was able to sleep was to stay awake for 24 to 36 hours and then pass out for 12 to 18 hours. I was miserable. I finally broke down my pride and went to see a sleep specialist. I implemented the sleep hygiene strategies and saw slight improvements but no major gains. I didn't have RLS or apnea, so the possible suspects were narrowing down. On a long shot we decided to try a medication called Rozerem. It's a synthesized melatonin available as a prescription. In most people the pineal gland regulates the sleep/wake cycle via the production of melatonin. As it turns out I have extremely low melatonin production, so my body never got the signal to shut down and sleep. With the introduction of melatonin in pill form about an hour before bed I was actually able to get a good night's rest. The difference was astounding. I had forgotten what being rested even felt like. Interestingly the melatonin had an immediate dramatic effect on me. It doesn't force drowsiness like a sedative does. It allows me to feel sleepy (rather than just tired or exhausted). Rozerem won't do anything for someone with normal melatonin production however. Past a certain level the body just metabolizes the extra melatonin and it is neutralized. For the same reason increasing the dosage of the medication won't have any effect.
For me the combination of improved sleep hygiene and the synthesized melatonin made a dramatic difference in my quality of life. Treating my father's sleep problems made him a much happier individual. If your doctor thinks that a medication for RLS will help you attain better sleep, I highly recommend that you at least try his suggestions. There is no substitute for being well-rested and you owe it to yourself to find out what will allow you to gain a good night's sleep.