i understand that you need sleep to function. i posit that it might be the case that you need *less* sleep for the same amount of function (energy, alertness), if physical activity was part of your day. i know it's the case for me that there are 3 factors i can tune and a couple i can't that affect how much sleep a "rested" me needs (not nodding off at work, in good spirits by default).

tunables:
- amount of intoxicants i consume. alcohol is not the worst offender here. can make a difference of up to +2 hours in my "how long do i sleep before i wake up naturally" number
- getting some exercise: at about 45 minutes, i take an hour off needed sleep to feel right. it also serves similar to a cup of coffee--doing it at 4am will rarely leave me able to sleep before 6am.

untunables:
- sickness
- stress
both lead to more sleep needed, or less good sleep being gotten in the same amount of time.

i am a sounds sleeper, so the following statement doesn't apply. but perhaps it is relevant to your situation, even if you've never realized it? are you getting good sleep? do you have apnea, do you have a dark room, a comfy relaxing bed, a quiet place? could be that moving off the main street would be all it takes for 6 hours of sleep to feel as good as 8.

luck++;

yup, this thread has my vote too. but you needn't follow anyone's formula, just find a way to work some miles into your life. i eat as much as i want and frequently drink a 6-pack of beer in an evening, and if i am a couch potato i swell up in short order. my office is less than a mile from home, so riding to/from work doesn't really put a dent in the waistline. however, there are times when i take the long way, and almost every day i do something other than go to work--be that go out to dinner, go shopping, go to friends' homes, the movies, whatever. and i ride there.

i grant you i have it super-easy since i moved to the most cycle-friendly city in the world, but i came from texas where i was frequently threatened by drivers and heat stroke and i did it there, too. definitely start with some advice from a local as to routes, or at least read http://bicyclesafe.com/ so you don't make any dumb moves or take any suboptimal routes (the interstate? almost always suboptimal.)

definitely do ramp up slowly (anything is better than nothing) to minimize discouragement and keep discomfort manageable. definitely do get a bike that's in decent shape--need not be expensive, needs be maintained regularly like a car (or maybe even more so--i pump up my bike tires weekly and reapply lube...welll..should be monthly). get appropriate clothing--this may not be spandex, but it is also probably not your work clothing. the pain you feel from the exercise shouldn't be surface or joint pain, it should be muscle pain. if you get joint pain, you might need to adjust the fit of the bike; surface pain suggests different clothing (i chafe between the thighs unless i wear spandex, be it under my clothes or exclusively, for instance). as well, bike sizing matters--every bike is not right for every person, and riding a badly sized one can injure you. so a little professional or amateur help (i hang out on some local general-interest message boards and offer to help people pick something sane from craigslist; i know others do the same in other locales. or just go to a bike shop & pay for the advice.)

these things will keep your riding more pleasant & safe.

good luck!

this site (smallnetbuilder) is the best i found doing research on similar topics recently. i am less concerned with bandwidth so was more interested in what's behind the curtain and featuresets which is covered well, but they certainly also have some bandwidth charts, including performance w/use of jumbo frames (which sounds like it might be of interest to you).