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According to: http://www.areyou-sleeping.com/SleepCycle.html
I think you guys are looking for something more than is reasonable to expect from a wrist band. To truly measure the various stages of sleep you need an EEG while jawbone 'infer' deep versus light sleep from body movement. I suspect it is quite possible that some individuals move more than others even when they are in one of the deeper sleep stages. As an earlier poster suggested I think the main benefit is to compare your own night by night readings and watch for trends that may indicate you are becoming more stressed (sleeping less well) etc.
According to the UP FAQ:
UP uses Actigraphy to track your sleep, monitoring your micro movements to determine whether you are awake, in light sleep, or in deep sleep.
According to a study published in Sleep, “How Accurately Does Wrist Actigraphy Identify the States of Sleep and Wakefulness?”:
Low PV’s and overestimation of sleep currently disqualify actigraphy as an accurate sleep-wake indicator. Actigraphy may, however, be useful for measuring circadian period and sleep-wake consolidation and has face validity as a measure of rest/activity.
I personally take UP’s sleep data with a grain of salt. For example, I know I did not fall asleep in 16 minutes last night. Like GadgetJohn suggests, I look at the trends and try to gain my own insights. Do I get more “deep” sleep after a day with lots of active time? Do I often have a less active day (and/or report my mood as “meh”) after a night of little “deep” sleep? That kind of thing.
Please respond to the question distinguishing Deep Sleep from REM sleep. If the Jawbone bracelet doesn't have the capacity to do that, just say so. If there is a percentage of REM sleep that can be figured from the time one is in Deep Sleep, please let us know that so that we can calculate appropriately.
From the solution to this thread, posted by JawboneAlex on January 2, 2013:
While you are asleep, UP monitors the amplitude, frequency, and consistency of your body’s movements to infer whether you are in deep or light sleep.… These classifications of sleep are intended for consumer sleep tracking to understand quantity and quality of sleep, and are not equivalent to medical sleep cycles and measures.
There is not a defined target for how much deep sleep you should be getting, though many users aim for 50% of their sleep to be deep. It may be valuable to consider your average deep sleep share over time to determine what level may be right for you and what factors affect the quality of your sleep.
Hmm.. thanks, editorgrrl, for finding the article from Sleep journal.
I note that this article is from 2001 --- 12 years ago --- and that the researchers employed one activity tracker (the 7164) that was an older model even at the time.
Potential improvements in monitoring technology since then may be significant. The researchers' suggested resaons for the poor ability of the activity trackers to predict sleep as defined by the EEG/Respiration monitors were:
1. The insensitivity of the activity monitors
2. The fact that activty monitors monitor activity (duh!) not sleep-as-defined-by-EEG/Respiration
[From the last page of their article] "We conclude that the predictive power of actigraphy remains limited by the sensitivity of current recorders and, more significantly, by the likelihood that motility carries sleep-wake information that differs from that of the conventional psg."
The second of these is not likely to have changed since 2001 (or earlier when the actual experiment was conducted) but the first may have. Current sensors and associated software may be better.
It would be interesting to know whether Jawbone believes their monitor's sensitivity for the kinds of actions implicated by sleep patterns is greater than the monitors used in the article.
© 2013 Jawbone.