The eyes: window to your soul and your drowsiness!

Learning about sleep and consequently human eye movement is truly fascinating! To think that during certain stages of the sleep cycle our eyes are darting around continuously – while we are in a deep sleep – is quite astonishing.

This week, we take a look at eye tracking and movements. Firstly we look at sleep, and how our eyes behave during the four different stages of a sleep cycle. Then we move to Optalert’s drowsiness detection glasses. How does eye tracking technology work in the Optalert system?

Eye movements while we sleep


Non Rapid Eye Movement (NREM) sleep comprises our four stages, NREM1, NREM2, NREM3 and NREM4. The first two stages are referred to as ‘light sleep’, while stages three and four are ‘deep sleep’. Your body makes its way through four NREM cycles, preparing itself for REM sleep.


REM stands for Rapid Eye Moment, and this stage is the fifth and final stage that makes up one sleep cycle.

During REM sleep, our muscles become paralysed, but the activity in our eyes and brain skyrockets. This is the stage of sleep where you normally experience dynamic dreams. Scientific research finds that although our bodies are virtually paralysed during this stage, our eye and brain activity is very similar to when we are awake.

Eye tracking with Optalert glasses

How do Optalert’s glasses track users’ eye movements? The glasses gather crucial information about a driver’s drowsiness levels.


Optalert’s glasses are worn just like any regular pair of prescription glasses or sunglasses. In fact, our frames can even be fitted with prescriptive lenses for those who need to wear glasses while driving.

While you are wearing them, the glasses unobtrusively measure your eyelid movements.

How they work

Using a tiny LED and sensor fixed into the glasses frame, Optalert’s glasses measure the rate at which your eyelids open and close, and track the saccadic movements of your eyes. Saccadic movement is your eyes moving quickly between two fixation points.  The sensor measures all these movements at a rate of 500 times per second!

What does the JDS™ mean?

So what happens to the data the LED and sensor collects?

It’s converted into a simple score from 0-10; this is Optalert’s JDS™. A score between 0 and 4.4 indicates ‘low risk’, a score between 4.5 – 4.9 indicates medium risk, and a score above 5 (and up to 10) is a high risk.


Drivers can self-assess their score while companies with fleet managers or supervisors also have access to their employees’ scores. From there, an appropriate course of action is taken.

The data provided by the JDS™ can help teams develop their fatigue management plan, designed to keep every single employee safe, whether they are going to work, at work or on the way home.

The glasses are unobtrusive and operate on a hands-free basis so drivers can perform their job as usual.

Measuring eye gaze vs. eye movement

Other drowsiness detection technologies measure gaze – that is, the direction of your eyes – whereas Optalert’s glasses measure the movement of your eyes – how fast and how far our eyelids open and close.

Others, in fact, do not measure your eyes, but rather your head movement.

That’s the difference between Optalert and other devices. Optalert is a world first in that it is the only drowsiness technology that can predictively assess how likely a user is to have a drowsiness-related accident or incident.

Tools that measure eye gaze fail to recognise normal driving actions like head checks, which can end up skewing data.

Contact Optalert today

Do you think Optalert’s eye tracking technology could help your employees? We’re in the business of protecting your people from the dangers of drowsiness. Contact Optalert now.