In today’s newsletter, we discover there is no safe amount of alcohol, learn the real way lice spread; find out why only some people go bald ... and serve up the surprising benefits of tennis. Plus, Kate Middleton’s good news; the fiber/colorectal cancer connection.

Buckle up: New research shows greater harm in even moderate drinking, women are more at risk, older people get a buzz faster, and don’t take a nip before bed. Plus, cancer. This roundup isn’t all bad news, with happy findings on the body’s resilience and new alcohol alternatives. Here’s what you need to know.

Related: Even a brief spell without alcohol can make dramatic changes.
Also: Why are more and more women dying from alcohol?
And: Cheap date? Why your liquor tolerance diminishes with age.
Um:  Should you smoke weed instead? Read this first.

Sleepless everywhere: Let’s face it—many of us are kind of la-de-dah about light pollution. It’s there, what can we do? New studies make clear what we should do to help our rest—and our health. How does light pollution hurt us? 

A. It gives us insomnia
B. It reduces melatonin
C. It could lead to cancer
D. All of the above 

Related: The toll that sleep apnea takes on a body.
Also: Can you sleep better if you tape your mouth shut?
And: The best organic mattresses for a good night’s sleep.

Did you know only half of Americans get enough fiber? Do you know colon cancer is now the No. 3 form of cancer—and it’s increasing among young people? Researchers believe lack of fiber and colon cancer are connected. How? 

What do you think? Do you have thoughts on today’s story about alcohol and the body? Let us know! We’ve already gotten a few replies, with a recently sober reader appreciating the support and another reader telling us to take it easy on wine, saying that winemaker Robert Mondavi made it to 94. (Point taken, and we found out Robert’s brother Peter lived to be 101.) Thanks for reading today’s newsletter, edited and curated by David Beard.

Today’s Soundtrack: No Return, Miles From Kinshasa