There are many ways to measure sleep deprivation.
One common way that researchers use is the Stroop Test (1). It’s a simple test where you see the names of colors, and have to identify not the name, but the color of the text.
For example, you might see the word “yellow” and have to answer “green”; the actual word doesn’t matter.
I’ve created a simple online version below, just click the button to begin when you’re ready. It measures both answer accuracy and speed of response. There are 50 questions in the test, which should take roughly 1-2 minutes to finish.
To answer each challenge, press the first letter of the color on your keyboard:
In order for this test to be useful in any way, you’ll need to repeat it for up to several days so you have results to compare against each other. Record your results in a spreadsheet or on a piece of paper.
You can also test your reaction time first thing in the morning, and see how much it slows down during different points of the day.
It’s not really fair to compare your results to others in isolation, because there are individual factors that aren’t consistent (i.e. some people are better typers than others, or have clearer monitor displays).
Below is a graph of results from a study that used this approach (2):
They kept subjects up for an extended period of time.
You can see that reaction time and accuracy both worsened right around the 16 hour mark, and then peaked around the 24 hour mark.
Again, it’s not fair to compare your results with the subjects in this study, but for a general reference, their “good” reaction times were around 850 ms for the incongruent Stroop test (which is the same approach as the test on this page).