After wearing various motion-tracking sleep monitors for two years, it's obvious they are not all created equally.

Some are more comfortable than others. Bands like the Jawbone UP24 are less intrusive to lie on than small pedometer-style gadgets like the Fitbit One, for example.

Accuracy varies too. Some devices require you to press a button to tell them that you're going to sleep, others automatically detect the diminished motion and start clocking sleeping hours.

I found the Misfit Shine and the Jawbone UP24 to be the most accurate, but neither allows you to do anything truly useful with the data.

The UP24 offers to wake you in the morning at the most appropriate time in a sleep cycle. It's great in theory, but if you happen to sleep in a bed with someone else, in practice the vibrating alarm wakes them when it wakes you, normally around 10 minutes before the alarm clock goes off, much to their annoyance.

But manually examining the sleep patterns the trackers capture over an extended period has allowed me to work out both how much sleep I really need to feel refreshed and what damages my sleep, making me feel tired throughout the day.

I need no more than seven hours 30 minutes of sleep, which gives me around four hours of so-called deep sleep. What I've noticed is that when deep sleep does not come in three large blocks I feel tired in the morning, no matter what my overall sleep time.

The temperature of the room, noise from outside, what time I go to bed and whether I've stared at a screen immediately before going to bed all affect those crucial three blocks.

I've also noted that alcohol in the evening prevents me sleeping well, while caffeine after about 1pm stops me getting fully to sleep in the first place.

Most of these observations could have been made without the bands, but having the gadgets track my sleep made me far more interested in my sleep and I now sleep better because of them.