If you're a little older than the target demographic and only receive information about TikTok when it leaks onto other websites, you might well think it's a site where people just sing sea shanties, hold the world's most deadly "jellyfish", and dip their balls in soy sauce to see if it's possible to taste using only your testicles.
There's more to it than that – but like the testicles tasting soy sauce hoo-ha, there is occasionally a bit of (largely harmless) misinformation that goes a bit viral on there. This week, it's people drinking lettuce juice in order to get to sleep.
TikTok user shapla_11 said in a video that "apparently drinking lettuce water makes you sleepy," adding, "sis don’t sleep so imma try it out".
The recipe, according to Shapla, is pretty simple. Merely take some lettuce, jam it in a mug, and pour over boiling "kettle water". She added peppermint tea, because she correctly identified that boiled lettuce might "taste like sh*t".
After ten minutes, she took out the floppy lettuce and gave it a go. She – and quite a few others on the site – claimed that it actually worked.
So, is lettuce actually some sort of sleep aid? No, probably not.
It's likely that somewhere along the line, someone on TikTok read (and misunderstood) a 2017 study on the sleep-inducing effect of lettuce in mice, given that a few of the participants of the challenge talked about using romaine lettuce specifically. Alternatively, they could have come across it in traditional medicine.
The study used sedative pentobarbital sodium to put the mice to sleep, as well as giving them extracts from the leaves and seeds of a few types of lettuce, in order to test whether the extracts improved the onset and duration of sedative-induced sleep. They found that extracts from the leaves and seeds of green romaine lettuce did improve the onset of sleep in the mice (who, again, had also been given a sedative) as well as sleep duration. This was put down to the lactucin content in the leaves and seeds compared with other lettuces.
However, it should be noted that the quantities involved in the study are not what the TikTokers appear to be ingesting. The mice were given doses of either 80 mg/kg of extract or 160 mg/kg. In an average person – weighing 62 kilograms (136 pounds) according to a 2012 study – that's 4.96 or 9.92 grams (0.17 or 0.35 ounces) of extract you would have to consume to get the same effect if you assume that it scales up precisely (which we cannot do).
The extract was also made using ethanol, rather than boiling water, to get much more lactucin out of the leaves and seeds.
In short, as the director of the Sleep Center of Excellence at Columbia University Irving Medical Center, Marie-Pierre St-Onge, told Insider, it's more likely that the TikTokers are getting an old-fashioned placebo effect from the lettuce water – especially the ones who are using the wrong type of lettuce.
They expect to feel sleepy, so they do.