Is The “Spoon Test” Actually Useful For Measuring Sleep Health?

Here’s the problem, though: “hours slept” is something you can objectively measure. “Goodness of a nap” is not. Are there any ways to scientifically evaluate the quality of sleep you’re getting?

In fact, there are – and the “spoon test” might be one of them.

What does the “spoon test” measure?

There are many facets to a good night’s sleep, but one that’s particularly revealing is your sleep latency, sometimes known as sleep onset latency. It’s “the length of time that it takes for someone to fall asleep,” Katherine Sharkey, associate professor of Medicine and Psychiatry and Human Behavior, and Medical Director of the Sleep for Science Research Laboratory at Brown University, tells IFLScience. “I would further specify and say it is the duration of time after the person is ready to fall asleep.”

What that means, she explains, is that we shouldn’t be counting the time we spend puttering about on our phones or watching TV – only the period in between deciding to close our eyes and actually nodding off. Generally speaking, you’re going to want that length of time to be less than 30 minutes – “if someone has a prolonged sleep latency for at least three nights per week for three months or more, that meets diagnostic criteria for insomnia,” Sharkey says.

Equally, though, you don’t want your sleep latency to be too short. “If sleep latency is so short that a person is falling asleep in the evening before going to bed, this is an indicator of poor sleep hygiene,” warns Sharkey. “Individuals who fall asleep on the couch before bedtime every night should think about going to bed earlier.”

Now, your sleep latency depends on quite a few things, and you probably shouldn’t freak out if you fall asleep as soon as you fall into bed every so often. It could be that you’ve had a tipple or two – alcohol, rather famously, reduces sleep latency quite effectively – or exerted yourself more than normal. It could be as simple as having stayed up a bit later than usual, and therefore being more tired.

Conversely, go to bed a little early, and you might find your sleep latency extending – you’re just not tired enough to fall asleep yet. There’s even a well-known phenomenon known as the “first night effect”, in which it often takes longer to fall asleep your first night in a new place.

Not all deviations in sleep latency are cause for concern, is the point. But a protracted period of low or high sleep latency might point to an underlying problem – or worse, cause one.

“In general, we recommend healthy adults obtain at least seven hours of sleep per night,” Sharkey tells IFLScience. “So if someone is only getting five hours per night and also notices that they are falling asleep as soon as their head hits the pillow, that’s concerning because the short sleep latency coupled with a pattern of inadequate sleep time points to chronic sleep deprivation and makes them vulnerable to a host of negative health consequences, especially falling asleep while driving. It also could be a sign of an undiagnosed sleep disorder.”

So, here’s the question: how do we measure sleep latency? It’s not exactly easy to record for yourself, since by design you’re asleep at the critical point. Neither is it necessarily something you can gather by vibes, since, paradoxically, we don’t always feel sleepy when suffering from sleep debt, the Sleep Foundation points out, and are rarely best placed to assess our own cognitive health.

Luckily – at least, if various online publications are to be believed – there is a solution: you just do the spoon test.

How does the spoon test work?

It’s pretty simple, actually: you just drop a spoon.

I have only heard of the spoon test being used to enforce brief daytime naps by famous creatives like Salvador Dalí and Thomas Edison.

Katherine Sharkey

Okay, yes, there’s a little more to it than just that. So, here’s the step-by-step deal: You’ll need a spoon, a watch, and a metal tray (or some other thing that would make a loud noise if a spoon were dropped onto it). Then, you simply “go to bed in the middle of the afternoon,” explained physician the late Michael Mosely in the 2017 BBC documentary The Truth About… Sleep. 

“Check the time, then shut your eyes,” Mosely continued. “When you fall asleep, the spoon should hit the tray – bang – and wake you up.”

At that point, you can check the time again, and work out how long it took for you to nod off – case closed. But is it as simple as all that?

Well, there are a few caveats. First, it’s important that you perform this test during the day, not at night – of course, we at IFLScience would never knock an experiment that involves taking a sneaky afternoon nap, but there’s a real reason for this: anybody can be tuckered out at night, after all, but if you’re unconscious before your head hits the pillow at 2:00 pm, then there might be something deeper going on.

Second, relying on your ability to hit a target simply by dropping a projectile, while falling asleep, is not necessarily a recipe for success. Perhaps the spoon will miss the tray; maybe you won’t drop it at all. In that respect, there might be an easier option, Mosely suggested: set an alarm for 10 or 20 minutes in the future, and see whether you fall asleep before it goes off.

Okay, but is the spoon test actually useful?

“I have only heard of the spoon test being used to enforce brief daytime naps by famous creatives like Salvador Dalí and Thomas Edison,” Sharkey tells IFLScience. “Legend holds that they would nap with a spoon in their hand and a metal pan underneath – so that when they fell asleep and their muscle tone decreased, the spoon would drop and the clatter of the spoon hitting the pan would wake them up.”

Basically, if you’re visiting the doctor for sleep problems, it’s unlikely they’ll suggest raiding the silverware drawer. That’s not to say tests for sleep latency don’t exist – they do, and they’re important diagnostic tools for problems like narcolepsy and hypersomnia – but they’re a clinical process lasting “most of the day” and requiring the help of “a sleep technologist [who] will gently place sensors on your head, face and chin,” according to the American Academy of Sleep Medicine (AASM).

“These sensors are connected to a computer,” the AASM explains, and “show when you are asleep and awake, and transmit data used to determine when you are in REM sleep.” Topping off all this monitoring is good old-fashioned eyeballs: “A low-light video camera will allow the technologist to observe your [test] from a nearby room.”

If that sounds quite a lot more involved than the spoon test – well, there’s a good reason for that. “The transition from wake to sleep is not perfectly synchronized across different brain networks,” Sharkey tells IFLScience. “We tend to think that falling asleep is like flipping a ‘brain off’ switch, but the spoon test illustrates that the sensation of cognitive disengagement from environmental stimuli that occurs at ‘sleep onset’ precedes the decrease in muscle tone that causes the person to drop the spoon.”

In other words, not only is the spoon test potentially difficult to pull off, but it’s also – even under the best circumstances – unlikely to be measuring exactly what it purports to. Falling asleep is simply a more complex process than spoons – or even more high-tech individual methods – can pick up on. 

“It makes sense that [the spoon test] might be seen as a way to measure sleep latency because wearables that track sleep seem to be ubiquitous,” Sharkey says. “But they are not particularly accurate when it comes to estimating sleep latency.”

Of course, none of this helps if you’re actually worried about your sleep latency – so what should we do if we’re consistently taking too long to drop off? Well, like pretty much all health advice, the answer is simple and (unfortunately) boring: “The best way to treat sleep onset insomnia is with behavioral strategies like keeping a regular sleep schedule, not trying to fall asleep until you are actually sleepy, and getting up and out of bed if you go to bed and can’t fall asleep in a reasonable amount of time,” advises Sharkey. “Also, avoiding excessive caffeine and daytime napping.” 

As for the opposite problem – falling asleep as soon as you crawl into bed, or even nodding off in the middle of the day – then “I [would] worry about inadequate sleep duration or an undiagnosed sleep disorder,” Sharkey tells IFLScience. “Definitely discuss [that] with your doctor!”