Is there something in lettuce that makes you sleepy? The truth behind the TikTok trend

December 20, 2025 •

4 min read

For thousands of years, some cultures have believed lettuce possesses sleep-inducing properties, with historical figures like the physician Galen reportedly consuming it to combat sleeplessness. This ancient belief recently resurfaced as a viral TikTok trend, making many wonder: is there really something in lettuce that makes you sleepy?

Quick Summary

Lettuce contains compounds like lactucin and lactucopicrin with mild sedative properties demonstrated in animal studies. However, the concentration in typical consumption is too low to reliably aid human sleep.

Key Points

Lactucarium, not lettuce, is the key ingredient: The milky white fluid, lactucarium, found in some lettuce stems contains compounds with sedative properties, not the leaf itself.
Scientific evidence is limited to animal studies: While concentrated lettuce extracts have shown sleep-inducing effects in mice, human trials on standard lettuce water are lacking.
The effect is likely a placebo: The calming ritual of drinking a warm beverage before bed, rather than the lettuce itself, is the most probable cause of perceived sleepiness.
Concentration is too low in homemade preparations: The amount of active compounds in a cup of homemade lettuce water is far too low to reliably induce sleepiness in humans.
Wild and specific cultivars are more potent: Wild lettuce species and specially bred varieties like Heukharang contain higher concentrations of sleep-related compounds, but are not what you find in a typical grocery store salad.
Proven methods are more reliable: For better sleep, focus on proven sleep hygiene habits, such as maintaining a consistent schedule and avoiding stimulants, rather than unverified trends.

The Science Behind Lettuce and Sleep

The idea that lettuce can promote sleep is rooted in the presence of a milky white fluid called lactucarium, which is secreted from the base of the stems of some lettuce species. This fluid is sometimes referred to as “lettuce opium” due to its purported sedative and pain-relieving effects. The primary chemical compounds in lactucarium thought to be responsible for these effects are lactucin and lactucopicrin.

Animal Studies and Human Limitations

Modern research has investigated these compounds, though most of the supporting evidence comes from animal studies, not human trials.

A 2017 study in mice found that extracts from romaine lettuce, especially green romaine, helped reduce sleep latency (the time it takes to fall asleep) and increased total sleep duration in mice that had been sedated with pentobarbital.
A subsequent 2021 study involving green lettuce leaf extract and mice similarly found that the extract promoted sleep through a GABAergic mechanism.

Crucially, these studies used concentrated extracts, not the quantities of compounds found in a few lettuce leaves steeped in water. Experts point out that extrapolating results from concentrated animal studies to mild homemade drinks for humans is not scientifically sound.

The Viral "Lettuce Water" Trend

The most recent surge in interest was driven by viral TikTok videos promoting "lettuce water"—hot water with steeped lettuce leaves—as a natural sleep aid. While many users reported feeling drowsy, sleep experts largely attribute this perceived effect to a combination of factors, primarily the placebo effect. The act of performing a calming bedtime ritual, like sipping a warm beverage, can in itself promote relaxation and sleepiness, regardless of the ingredients. The actual amount of lactucarium that would be released from a few leaves is considered too insignificant to have a powerful sedative effect.

Comparison of Sleep Aids: Lettuce Water vs. Proven Alternatives

To understand the context of lettuce water, it's helpful to compare its scientific backing to that of other, more established sleep aids. This table provides a quick overview:


Feature	Lettuce Water (TikTok Trend)	Chamomile Tea	Melatonin Supplements	Sleep Hygiene Practices
Primary Mechanism	Low concentration of lactucarium (likely placebo)	Apigenin binds to benzodiazepine receptors	Regulates the sleep-wake cycle	Behavioral and environmental changes
Scientific Evidence	Minimal to none for humans	Moderate, some human studies exist	Strong, many randomized controlled trials	Strongest evidence, medically recommended
Concentration	Very low	Effective concentration	High, standardized doses	N/A
Taste	Often described as bland	Mild, floral, pleasant	Flavorless capsule or pill	N/A
Risk of Side Effects	Very low (unless contaminated)	Very low, possible allergic reactions	Possible daytime grogginess or headache	None
Effectiveness	Highly variable, likely placebo-driven	Moderate, helps with relaxation	High for some sleep issues	High and sustainable

What Types of Lettuce are Most Potent?

Not all lettuce varieties are created equal when it comes to the compounds associated with sleepiness. Historical use and some limited studies suggest that wild lettuce (Lactuca virosa) contains significantly higher concentrations of lactucarium than the common cultivated varieties.

Wild Lettuce (Lactuca virosa): This species has the highest concentration of lactucarium and is the source of the term "lettuce opium." It was historically used as a folk remedy for its sedative properties.
Romaine Lettuce: Research on mice has shown that romaine lettuce, particularly the green variety, contains more lactucin than other common types. However, this is still a negligible amount compared to concentrated extracts.
Specialty Cultivars: A 2025 human clinical study focused on a Korean lettuce variety called 'Heukharang' which was bred to have extremely high concentrations of lactucin. The study found significant improvements in sleep quality and quantity using a potent extract of this specific lettuce, demonstrating that higher doses can have an effect.

Natural Alternatives and Best Practices for Better Sleep

Instead of relying on the unproven effects of lettuce water, there are many evidence-based strategies for improving sleep. For those struggling with consistent sleep issues, these methods are more reliable.

Best Practices for Sleep Hygiene:

Maintain a consistent sleep schedule: Go to bed and wake up at the same time each day, even on weekends.
Create a relaxing bedtime routine: Incorporate calming activities like reading a book, taking a warm bath, or listening to soothing music before bed.
Optimize your sleep environment: Keep your bedroom dark, quiet, and cool.
Avoid stimulants before bed: Cut out caffeine and nicotine several hours before you plan to sleep.
Limit alcohol intake: While alcohol can make you feel drowsy, it disrupts sleep cycles and can lead to restless nights.

Conclusion

While the folklore and anecdotal evidence surrounding lettuce's sedative properties are intriguing, the scientific consensus is clear: the amount of sleep-inducing compounds present in a glass of homemade lettuce water or a typical salad is far too low to have a meaningful effect on human sleep. The observed drowsiness reported by some is most likely a result of the placebo effect or the relaxing nature of a warm nightly beverage. For those seeking a genuine and effective solution to sleep problems, investing in proven sleep hygiene practices or exploring evidence-based natural alternatives like chamomile tea is a far better use of time and effort. The case for lettuce as a common and effective sleep aid, outside of highly concentrated extracts from specific varieties, remains firmly in the realm of myth rather than scientific fact.

Sleep Promoting Effects of Lettuce (Lactuca sativa L.) Extracts in Korean Adults with Poor Sleep Quality: A Randomized, Double-Blind, Placebo-Controlled Trial

Frequently Asked Questions

Lactucarium is a milky white fluid secreted from the stems of some lettuce species, particularly when the plant is flowering. It contains compounds like lactucin and lactucopicrin, which have historically been noted for their mild sedative effects.

Scientific studies suggest that wild lettuce (Lactuca virosa) contains the highest concentration of lactucarium, followed by romaine lettuce. However, the amounts found in cultivated varieties are not high enough to act as a reliable sleep aid.

It is unlikely. Research indicates that the concentration of sedative compounds in homemade lettuce water is too low to produce a noticeable sleep-promoting effect. A large portion of the reported effects are likely due to the placebo effect.

For most people, drinking lettuce water is harmless, provided the lettuce is thoroughly washed to avoid foodborne illness. However, those taking anticoagulant medications should be cautious, as lettuce contains vitamin K which affects blood clotting.

Lettuce contains lactucarium, which is sometimes called 'lettuce opium.' However, this comparison is a misnomer, as the sedative effects of the compounds in lettuce are extremely mild and not comparable to pharmaceutical opium.

Evidence-based alternatives include practicing good sleep hygiene (consistent schedule, dark room), drinking chamomile tea, using melatonin supplements, and avoiding stimulants before bed.

No, eating a large meal right before bed can actually disrupt sleep. While lettuce is nutritious, its sleep-inducing effects are negligible. For some sensitive individuals, a large quantity of fiber from salad could even cause digestive discomfort.