I saw this cute online sleep calculator. They claim (put in any time, and you'll see it):

The average adult human takes fourteen minutes to fall asleep, so plan accordingly!

Is this correct?

  • 1
    I assume this means that a human takes 14 minutes to fall asleep on average: there is no such thing as an "average human", strictly speaking :-) – Sklivvz Jan 23 '14 at 13:27

The term for this time is "sleep latency". (Actually Wikipedia prefer Sleep Onset Latency but that doesn't match the literature I was finding.)

The calculator makes predictions down to the minute based on this estimate. The figure is not that predictable or precise.

Practice Parameters for Clinical Use of the Multiple Sleep Latency Test and the Maintenance of Wakefulness Test is a discussion on the Multiple Sleep Latency Test - where patients are given several opportunities throughout the day to fall asleep, and their sleep latency is measured.

In Table 3, it gives mean sleep latency of 10.4 +/- 4.3 minutes or 11.6 +/- 5.2 minutes, depending on the protocol used.

In Meta-Analysis of Quantitative Sleep Parameters From Childhood to Old Age in Healthy Individuals: Developing Normative Sleep Values Across the Human Lifespan they look at how sleep latency changes over time and between genders.

Overall, it appeared that sleep latency modestly but significantly increased with age. However, the change is very subtle [...] The overall increase in sleep latency between 20 and 80 years was less than 10 minutes.

They also showed men have higher mean sleep latency.

In Figure 1A they showed a scatterplot which gives a good idea of the range (and trends). Note the trend line is somewhat higher than the previous reference.

Scatterplot from Figure 1a

In summary: 14 minutes is around the right time, but planning your alarm clock wake-up time based on such a precise figure isn't warranted.

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    Sleep latency is best measured during the day, not at the time when one would normally be trying to go to sleep, so this is measuring something different than what the website in the question is relying on. – user5582 Jan 23 '14 at 17:09
  • @Articuno: The Multiple Sleep Latency Test (first reference) is indeed done several times throughout the day. The second reference talks about '“all-night” PSG or actigraphy', which I interpret as close to what the website was talking about. (I have never understood how they deal with the 'first night in a new bed' sleep issues, but that's another story.) – Oddthinking Jan 23 '14 at 21:46

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