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Let Us Talk About Lettuce Water

When it comes to drinking lettuce water for a lullaby, I say good bye to the idea.

Macbeth knew about sleep deprivation, as we can infer from his thoughts in the second scene of Act 2.  

Sleep that knits up the raveled sleeve of care, 

The death of each day's life, sore labor's bath, 

Balm of hurt minds, great nature's second course, 

Chief nourisher in life's feast. 

If the Thane of Cawdor were around today, he might take some advice from the numerous Tik Tok videos that sing the praises of lettuce water in the battle against insomnia. Somewhere between ten and thirty percent of the world population is engaged in this battle and often look to “natural” substances such as melatonin or extracts of St. John’s Wort, kava, passionflower or valerian root for help. They rarely find it. Therefore, it isn’t surprising that may latch on to the seductive Tik Tok videos that promise sweet dreams by drinking water in which lettuce has been boiled. But is the prospect of sweet dreams just a dream? If I had to wager on this, that’s the way I would bet. 

As with so many of the far-flung videos that badger the brains of Tik Tokers, there is a seed of truth, but the seed is likely to be infertile. In this case the seed was planted by a Korean study that investigated the sleep-inducing effect of lettuce. In mice! Why did they do this? Because apparently lettuce seed oil has a history of use as a pain killer and sleeping aid in folk medicine. As far as science goes, one study did find that a couple of compounds in lettuce, lactucin and lacucopicrin, can reduce pain and anxiety in rats.  

The Korean researchers thought this was worth further exploration and chopped up some lettuce and lettuce seeds, dried them and circulated a mixture of water and alcohol through then for four hours. They then fed the extract produced to mice before treating the animals with pentobarbital to induce sleep. They then measured the time it took for the mice to fall asleep as well as the duration of their sleep and compared these to mice that also received the drug but not the lettuce extract. The control mice fell asleep in about 75 seconds and the lettuced mice in 50 seconds. The latter also slept about 70 minutes before waking compared with an hour for the controls. Another part of the study involved drilling holes into the skulls of the anesthetized mice and implanting electrodes to measure rapid eye movement (REM) sleep, an indicator of shallow sleep.  The mice that had been supplemented with lettuce reduced their REM sleep time, suggesting a deeper, more restful sleep. 

Let’s try to introduce a little perspective here. First, the lettuce used by the scientists was green romaine, since they had found it to have significantly more lactucin and lacucopicrin than any other type of lettuce. And extracting chopped lettuce or seeds for four hours with an alcohol-water mixture in the lab is decidedly different from brewing a few lettuce leaves, not romaine in most videos, for a few minutes in hot water. Neither is pentobarbital induced sleep comparable to natural sleep. Then we must note that people are not mice, and the effect of lettuce extract on the brain waves of mice cannot be extrapolated to humans. Human brains are more sophisticated than mouse brains. (Although not necessarily in all cases.) 

So, I don’t think this study provides much of a basis for torturing the palate with lettuce water. I would gladly change my opinion if a study in humans with a standardized extract of romaine lettuce demonstrated an effect on insomnia. Some sleep researcher should take up the challenge and carry out a human study. There would be no shortage of volunteers. Given that I often wake up at 4 am and have a hard time going back to sleep, I’d be at the head of the line. Or maybe I should just stop the habit of falling asleep with television and computer screens lighting up the bedroom. 

As for Macbeth, had he not killed Duncan, he wouldn’t have had to worry about insomnia. 


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