There are a number of products on the market that claim to be "better alarm clocks" that allows you to feel more refreshed when you wake - even if you sleep a few minutes or tens of minutes less.

There are two claims:

  1. that one feels more refreshed if one wakes during the REM phase of a sleep cycle, and

  2. by monitoring movement as one sleeps, devices can determine the sleep cycle.

Examples of products that make such claims include:

SleepTracker’s SmartStart Technology monitors your sleep stages throughout the night and then uses that data to determine the exact moment when you should be awoken helping you feel refreshed and energetic. 1

Do these alarm clocks really make you feel more refreshed? Is such a thing feasible?

  • Where can you get one of those devices that logs your sleep pattern to a computer?
    – SteveGSD
    Jun 25, 2011 at 3:48
  • Skeptics is for claims researching the evidence behind the claims you hear or read. It is not for idle speculation. Have you heard or read someone claiming, or is this just mere curiosity? If the former, could you provide us with a link to the claim or expend on the context where you encountered it? It would be helpful.
    – Borror0
    Jun 25, 2011 at 4:05
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    I have added links (not comprehensive) to products that make these claims. Jun 25, 2011 at 4:37
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    You have to add a link to what I thought was the most prominent of all! Zeo: "Zeo is designed to help you analyze your sleep and improve it, so you can be your best...Zeo will tell you your ZQ — a number that summarizes your sleep’s quantity and quality...If you can measure it, you can improve it...Zeo Personal Sleep Coach will help you understand and minimize the factors that negatively affect sleep, so you can take control of your nights. You can use the visual analytical tools...to see trends and cause & effect patterns."
    – Hendy
    Jun 25, 2011 at 4:43
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    If you look at one of the top amazon reviews for Zeo, it says that it reported that he was asleep and had REM / light sleep cycles even though he was wide awake the whole time.
    – SteveGSD
    Jun 25, 2011 at 21:22

2 Answers 2


This article may be enlightening.

The most accurate method of measuring someone's sleep cycle is to use a bunch of electrodes attached to a person's head - I did this once. It's difficult to sleep this way because the gunk gets in your hair and restricts your movement in the night. However, measuring a person's movement during sleep - which is what all of these devices are doing is also very accurate.

This paper, claims to be able to accurately detect REM sleep from actigraphy and pulse monitoring.

Waking at the right cycle during sleep reduces sleep inertia - the feeling of grogginess. Here's a source explaining sleep inertia.

It is possible to fairly accurately monitor sleep cycles using activity, and waking up in the certain sleep cycles reduces grogginess, so their claims are plausible

  • FYI Zeo uses EEG based monitoring to detect sleep phases.
    – redcalx
    Mar 10, 2013 at 2:57

The gold standard for measuring or monitoring sleep is Polysomnography (PSG for short).

However as Catherine says it's quite a cumbersome procedure. It monitors many vitals like EEG, EMG, Oronasal respiratory rhythms. Researchers have that's why tried a lot to analyse sleep using other easily available human vital signs. Accelerometry or Actigraphy (measuring body movement) gives valuable information on the depth of sleep.

That was the essence of all first generation research starting from 1960's until almost 2004. But now-a-days, few researchers have showed that it's possible to analyse sleep into 4 NREM (Non Rapid Eye Movement) and REM and a wake phase using the Heart Rate Variability (HRV).

There are numerous devices in the market that claim to analyse sleep. Most or all of them output various measures related to sleep efficiency. I'm currently doing a literature survey on the topic. In near future, we intend to devise our own algorithm that can do this in an effective way.

Btw, I'm a bio-medical algorithm developer.

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    Can you reference all facts in your answer? If you do this would be a good answer.
    – Wertilq
    Jul 4, 2013 at 16:31

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