I came across the Lifestream of Acetuk and saw this interesting post with his sleep pattern:
A little more sleep but still erratic –
Sleep statistics for 13 – 14 Jan (Thu).
Went to bed / woke up: 01:34 / 06:21
Total time: 4h 47m
It also included this image:
Turns out he is tracking his sleep patterns with an iPhone app called Sleep Cycle. Anyone try this out? It looks interesting.
You can find many more sleep apps and devices in the Lifelogging / Quantified Self section.