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Why Your Sleep Target Isn't Eight Hours

Sleep1 min readHirshkowitz et al., Sleep Health (2015)

Individual sleep need varies by well over an hour between healthy adults, so a fixed eight-hour target tells a natural seven-hour sleeper they are chronically short and a natural nine-hour sleeper that they are fine. Kriterion learns your target from your own nights instead, though not from your average, and the distinction matters more than it sounds. Habitual sleep is curtailed sleep for most people: alarms, commutes, screens and children all mean the average measures what your life permits rather than what your body needs. Targeting that average would hand a chronically short sleeper a target they already meet and score them full marks for a deficit.

So the target is taken from the upper part of your own distribution, meaning the nights nothing stopped you, and then held inside the 7 to 9 hour adult range. The app can learn where you sit within a healthy range; it should not learn that your deficit is your normal. Tracker glitches are filtered out first, so a watch left on charge overnight does not quietly become your new target.

How Kriterion uses this

Kriterion learns your sleep target from your own nights, from the upper part of your own distribution rather than its average, and holds it inside the healthy adult range.

References

  1. Hirshkowitz M, Whiton K, Albert SM, et al. National Sleep Foundation's sleep time duration recommendations: methodology and results summary. Sleep Health, 2015;1(1):40-43.
  2. Watson NF, Badr MS, Belenky G, et al. Recommended amount of sleep for a healthy adult: a joint consensus statement of the AASM and SRS. Sleep, 2015;38(6):843-844.
  3. Van Dongen HPA, Maislin G, Mullington JM, Dinges DF. The cumulative cost of additional wakefulness. Sleep, 2003;26(2):117-126.
  4. Klerman EB, Dijk DJ. Interindividual variation in sleep duration and its association with sleep debt in young adults. Sleep, 2005;28(10):1253-1259.

Kriterion is the app this reasoning is built into

It measures your maintenance calories from what you actually ate against what the scale actually did, tells you how firmly the number is pinned down, and checks its own past predictions against your results. Free logging, UK food data, and no ads.