Determining your optimal nap length.

If you are doing any sort of polyphasic sleep, or for that matter, even monophasic sleep, it is beneficial to wake at the end of a full sleep cycle, rather than have your alarm interrupt a cycle. Waking at the end of a cycle means that your mind comes easily out of REM and into consciousness. There is reason to think that you get only minimal, if any, benefit from cycles that are interrupted and that interrupted cycles contribute to sleep deprivation.

There are a couple of ways make sure that you are waking at the end of a full cycle. Probably the best available method is to purchase a Zeo. This device not only monitors the depth of your sleep and will awaken you during your lightest sleep, it also maps your sleep cycle and creates a hypnogram. Since the Zeo determines your sleep depth directly from your brainwaves, it is by the far most accurate method of tracking your sleep outside of a sleep laboratory.

Kitten don't need no Zeo.

A second option is a new app for the iphone. Sleep Cycle uses your movements to determine which sleep phase you are in and then wake you at an appropriate time. At $.99 it is much more affordable than the Zeo, if you already own the iphone. 

Which I don't, because I live in the boondocks and I only get cell service through US Cellular. I also have not sprung for a Zeo, so I came up with a frugal, low-tech method of determining my optimal nap length. I found an alarm setting that would wake me up, but ONLY when I was already in a very light sleep. My alarm is my cell phone (an old clunky one) set on Vibe Dot Dot and tucked under my pillow. When I was first trying this schedule, I would set 4 alarms spaced 2 minutes apiece. Each alarm will ring three times, 9 minutes apart, so I would get a vibrating alarm every 2 minutes over the course of 35 minutes. When I woke up, I would note the time, hone my sleep schedule that way. I started out with 3x90 since 90 minutes is a typical sleep cycle. After measuring for a few days, it turns out that my evening and morning sleep schedules are 80 and my afternoon nap is 55 minutes. These are still just averages, and not as good as using the Sleep Cycle app or the Zeo. My actual nap needs seem to fluctuate a bit depending on exactly when I got up from my last nap and the time that I went to sleep for my current nap. So, sometimes, I will be a bit off from my schedule. That inevitably seems to mean that I will not wake naturally and will need my alarm. On the occasions that I do use my alarm, I am often a bit groggy, but if I get up, have my coffee and move around a bit, I can shake it off. I think the only way to not have an occasional groggy "morning" is to either be very consistant on your schedule, or to use a Zeo.