A chemical found in fish could help reinvent your sunscreen

A solution for California's water woes

For years, farmers in California have been pumping huge amounts of water from their wells to irrigate their crops. The state’s Central Valley is the nation’s single biggest source for many different foods. But all that water use is making aquifers shrink [https://water.ca.gov/Programs/Groundwater-Management/Bulletin-118/Critically-Overdrafted-Basins], wells go dry and, in some places, the ground sink. Science reporter Dan Charles [https://site.danielcharles.us/] has been looking into the issue and is on the show today to talk about what happens when water gets scarce. What is it like for farmers? And for the people enforcing new water restrictions?  If you liked this episode, check out some of our other recent water stories – including why the world’s freshwater is getting saltier [https://lnk.to/7Mz2Ng], what’s happening to our groundwater supply [https://lnk.to/os7Fci], and what happens when a city runs out of water [https://lnk.to/Ty93au]. Interested in more stories about water, farming and food production? Email us your question at shortwave@npr.org [shortwave@npr.org]. Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave [http://plus.npr.org/shortwave]. See pcm.adswizz.com [https://pcm.adswizz.com] for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences. NPR Privacy Policy [https://www.npr.org/about-npr/179878450/privacy-policy]

What's up with your nightmares?

Dreams of flying? Nightmares of teeth falling out? Falling off a cliff? As a sleep scientist at the University of Montreal, Michelle Carr [https://recherche.umontreal.ca/chercheur/is/in35846/] has pretty much heard it all. In Michelle’s new book Nightmare Obscura [https://us.macmillan.com/books/9781250342720/nightmareobscura/], she explores the science of dreams, nightmares – and even something called dream engineering, where people influence their own dreams while they sleep. Today on Short Wave, co-host Regina G. Barber [https://www.npr.org/people/1082526815/regina-g-barber] dives into the science of our sleeping life with Michelle Carr. (encore) Interested in any upcoming science books? Email us your question at shortwave@npr.org [shortwave@npr.org]. Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave [http://plus.npr.org/shortwave]. See pcm.adswizz.com [https://pcm.adswizz.com] for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences. NPR Privacy Policy [https://www.npr.org/about-npr/179878450/privacy-policy]

A chemical found in fish could help reinvent your sunscreen

It’s been over 25 years since the FDA approved a new ingredient for sunscreen in the United States. But a molecule called gadusol found in fish and coral reefs is a promising candidate. It absorbs U.V. rays — acting like a built-in sunscreen for fish. But there’s a big hurdle if scientists want to turn gadusol into human sunscreen: They’d need to make a lot of it. A new study [https://www.cell.com/trends/biotechnology/fulltext/S0167-7799(26)00098-3?] out this week in the journal Trends in Biotechnology takes us a big step closer. Their solution? Using the bacteria best known for making your stomach hurt: e. Coli.  Interested in more science? Email us your question at shortwave@npr.org [shortwave@npr.org]. Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave [http://plus.npr.org/shortwave]. See pcm.adswizz.com [https://pcm.adswizz.com] for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences. NPR Privacy Policy [https://www.npr.org/about-npr/179878450/privacy-policy]

Should you be fibermaxxing? Here's what the science says

The average person eats 10-15 grams of fiber per day, according to the USDA. The problem? That’s WAY under the recommended daily amount. Fiber – a type of carb that our bodies are unable to digest – is prevalent in foods like fruits, veggies, whole grains, and beans. And it’s key for everything from feelings of fullness, to gut health, to good poop. That’s why a lot of people online are “fibermaxxing”: trying to meet or exceed the daily recommendation of fiber, in hopes it’ll improve their health. But how should YOU add fiber to your diet… and are the fibermaxxers overdoing it? Gastroenterologist Berkeley Limketkai [https://www.uclahealth.org/providers/berkeley-limketkai] is here to help parse the science on how little fiber is too little, how much fiber is too much – and, like Goldilocks, how we can figure out the amount that’s just right. Interested in more food and dietary science? Email us your question at shortwave@npr.org [shortwave@npr.org]. Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave [http://plus.npr.org/shortwave]. See pcm.adswizz.com [https://pcm.adswizz.com] for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences. NPR Privacy Policy [https://www.npr.org/about-npr/179878450/privacy-policy]

Why Swedish scientists gave salmon cocaine

A recent study [https://doi.org/10.1016/j.cub.2026.03.026] caught our eye: salmon on cocaine. Or really, researchers giving salmon cocaine…for science. See, scientists know human drugs pollute aquatic environments – past studies have shown even anti-anxiety drugs [https://doi.org/10.1126/science.1226850] can change how fish act. But illicit drugs are less studied. And Jack Brand [https://www.slu.se/en/profilepages/b/jack-brand/], an aquatic ecologist at the Swedish University of Agricultural Sciences, wanted to know how illicit drugs like cocaine might change fish behavior, like foraging and mating. To answer that question, Jack and his team gave salmon cocaine.  Interested in more science? Email us your question at shortwave@npr.org [shortwave@npr.org]. Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave [http://plus.npr.org/shortwave]. See pcm.adswizz.com [https://pcm.adswizz.com] for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences. NPR Privacy Policy [https://www.npr.org/about-npr/179878450/privacy-policy]