Nivedit Majumdar Nivedit Majumdar

Sleep Tracking- Quantifying naps

If we had to sum up the purpose of the Quantified Self movement in two words, it would be ‘Know thyself’. The underlying purpose of Quantified Self is to get a deeper insight into the functioning of the human body, and a key aspect of this is to gather as much data as possible. While fitness trackers, activity trackers and monitors are conducive to taking in as much information as possible, another important type of monitor is active when we are not. Yep, I’m talking about sleep trackers.

So this is the crux of my article here. I delve deep into sleep tracking: what is the purpose, what are the terminologies associated, and how do they work. Sleep is an important aspect of quantified data, and I discuss all this in my article here.


Health tracking might be relevant, but the relevance of sleep tracking is a concept that is tad bit more abstract. To understand why Sleep Tracking is needed, let’s understand the effects of insomnia first.

A recent CDC report stated that America’s sleep problem is a public epidemic, and this causes a loss in economic productivity (to the tune of billions of dollars), obesity problems, diabetes and heart disorders and boosts to the immune system.

In fact, a projection for diagnostic devices monitoring sleep disorders are stated to grow to large numbers in 2017, as evident from this graph.

(Data Source: Statista)

All in all, a multitude of problems are associated with the lack of sleep. And the first step of combating the problems is to monitor and analyse the sleep patterns.


Sleep itself is of various forms, and sleep trackers and sensors are equipped to track and monitor all these forms.

In a nutshell, these are the types of sleep forms.



This is the type of sleep wherein the body is at its most relaxed state. It is essential for waking up energized and refreshed, and it helps in maintaining a certain level of health. Typically, it ranges from 15 – 30% of a night’s sleep.


It constitutes the majority of the night’s sleep. It denotes the transition of the sleep from the deep and REM patterns.


Rapid Eye Movement Sleep is a unique phase of sleep characterized by random movement of the eyes, low muscle tone throughout the body, and the propensity of the sleeper to dream vividly. This phase is also known as paradoxical sleep (PS) and sometimes desynchronized sleep because of physiological similarities to waking states, including rapid, low-voltage desynchronized brain waves. (Source: Wikipedia)


Again, there are a few types of sleep trackers. Most of the sleep trackers in the market are forms of either type.



These kind  of trackers have a button which the user must press to enable sleep tracking on the fitness monitor. Needless to say, this feature comes bundled with most fitness trackers capable of tracking sleep.


Here, there is a software element involved, where a particular time frame is defined as the ‘sleep time’ (typically between 12am and 6am). The tracker will sense for sleep only in this defined period, and this feature has the advantage of saving the battery power.


Sleep trackers are surprisingly accurate. In Feb 2014, Dr. Christopher Winter underwent a sleep test, with various sleep trackers along with a polysomnogram .These are the comparative results.

(Data Source: Huffington Post)

The readings speak for themselves, and the they have been found to be most accurate when taken from the sleep trackers, and least when taken from the smartphone application.


Typically, it’s mainly an accelerometer in the sleep tracker, but more scientific modules incorporate brain wave studying, eye movement, actigraphy, heart rate and muscle tension. Interestingly, the factor of muscle tension causes the person to dream that he/she is ‘falling’!

With the advent of the Internet of Things, more complex sensors are getting a more compact form factor, and they are now being incorporated into pillows and mattresses as well.


Sleep tracking has a very bright future. Big corporations like Apple and Google are jumping on the whole health/sleep tracking bandwagon, with software development suites dedicated only to these things. And with the popularisation of Quantified Self, sleep tracking can only become more mainstream in the future!

[Continued- The Science behind sleep tracking]

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