Week 2 Lab: What Is "Tired"?
This week
Before you can measure how tired you are, you have to decide what you mean, and that decision quietly settles what you are able to find.
What you bring to the lab
The lesson below is how you get there. The lab is where you show it.
- you bring three candidate measures of tiredness, not one
- each one can be recorded in under thirty seconds
- you can name something each measure would miss
“I’m tired” is not a measurement. It is a report, and a compressed one: it can mean your eyes hurt, or you are bored, or you have been awake for nineteen hours, or you do not want to do the thing you are about to do.
To operationalise a word is to decide which of those you mean, and to pick something you can write down. The decision looks like bookkeeping. It is not. It settles in advance what your experiment is capable of noticing.
Three ways to be tired#
Bring three candidates to the lab. You will find they disagree, which is the useful part.
- Ask yourself. A number from one to seven, recorded four times a day. Fast, free, and the thing almost every study relies on.
- Time something. How long it takes you to react to a light, or to read a paragraph, or to fall asleep. Slower to collect, harder to argue with.
- Count a consequence. Typing errors. Times you reread a sentence. Times you walked into a room and forgot why.
Why this is the week it matters#
There is a well-known sleep restriction study in which people spent two weeks on four, six or eight hours in bed. Their own sleepiness ratings rose sharply for a few days and then flattened out. After a while, four hours and six hours felt about the same. Their measured performance did not flatten out. It kept declining, steadily, the whole time.
The people in that study were not lying and they were not careless. They had simply lost the ability to feel the thing that was happening to them. If the only measure you carry is “ask yourself”, there is a version of tiredness you are structurally unable to detect.
Your week 1 record already has some version of this in it. Most people wrote something like “flat” or “fine” at some point on that day. This week you decide what you would have to have written down instead.
The trap#
You will be tempted to pick the measure that is easiest to collect and then quietly treat it as though it measured everything. Everybody does this. The defence is to write down, now, one thing your chosen measure cannot see, and to keep that sentence next to your results for the rest of the semester.
Evidence on file
- 48 people not blinded
Under two weeks of restricted sleep, people's ratings of their own sleepiness levelled off after the first few days while their measured performance kept getting worse. The authors concluded subjects "were largely unaware of these increasing cognitive deficits".
Van Dongen HPA, Maislin G, Mullington JM, Dinges DF, The cumulative cost of additional wakefulness, Sleep 2003;26(2):117-126. The n of 48 covers both the restriction and total-deprivation experiments together.
Teaching team
- Tobias Veck, tutor