set: Don't worry about it. If you're still looking for a way to reduce your sleep hours without disrupting normal life, you might consider biphasic with a 3- or 4.5-hour* core sleep at night and then a 1.5-hour* nap during the afternoon or evening. This is probably the most "natural" sleep method you can achieve while using an alarm clock (the body's circadian rhythms are tailored toward this sleep schedule, with a major, prolonged drop in body temperature at night and a lesser, short drop in body temperature in the early afternoon). There will still be an adaptation period that you need to force your way through, but it shouldn't be nearly as tough as polyphasic, since it's not too far removed from monophasic sleep.
* I use multiples of 90 minutes for the nap and sleep times here because that's the average length of the sleep cycle (during long sleep periods; not applicable to polyphasic). This way you wake up at the beginning/end of a cycle, when it's easy to do so. If you wake up in the middle of the cycle, it will be harder to wake up and you'll have much less energy for your day. This is why people can get seven hours of sleep and still be tired!
Ati: From personal experience, the gradual method is easier because at first it's easier on your body. It does eventually get comparably difficult to the cold turkey method, but at least you have some time to work your way up to it. I suspect gradual adaptation takes longer, though (I can't say for sure because when I tried it last summer, I gave up before the adaptation was done). If you decide to use that method, I would point you to this page
, which includes a description of the transition used for Claudio Stampi's 48-day study of polyphasic sleep.
As regards methods for getting up at 3:45--these are good techniques for waking up from polyphasic naps also. The only exception regards coffee, or rather caffeine in general: in a monophasic schedule you're awake long enough that caffeine in the morning or day is out of your system by the time you go to bed in the evening, so it's not a major problem. However, on a polyphasic schedule, it's best to avoid it, as it's almost impossible for caffeine to get out of your system in time to not interfere with your next nap.
If you decide to try polyphasic sleep, please write in to say how it goes!