Advice for those who are interested in trying Biphasic sleep

I began this under the assumption that I have the average 90 minute cycle. However, it may not be the case. If you want to learn what your 5 stage sleep cycle is (usually between 70 to 110 minutes), try this: go to bed like normal, but remember at about what time you fell asleep. Once you naturally wake up (obviously, no alarm clock), calculate the time you were asleep and try to find a multiple of 70-110 that fits. Do this a few times to get a good idea of your cycle length. Then, you can customize your biphasic pattern in multiples of your cycle length. It seems that most people (myself included) follow the system of 2 cycles for nightly core sleep and 1 cycle for evening nap. Once I get adjusted to this schedule, I should be able to use the same method for calculating my cycle, but I don't think I should trust myself without a clock just yet...