Cut From Steel

32 DAYS IN A CAVE. THEN 104 YEARS.

Nathaniel Kleitman wanted to know whether a man could live on a 28-hour day. In June 1938 he went underground to find out. He and a 20-year-old student named Bruce Richardson moved into Mammoth Cave in Kentucky.

The cave had no sunrise or sunset to set their clocks. Kleitman and Richardson followed a schedule of nine hours of sleep, ten of work, and nine of rest. They stayed down there for about 32 days. Picture a month with no daylight at all.

Richardson adapted in about a week. Kleitman was 43 and never did. His body kept its own clock no matter what the schedule said. Kleitman came out with a lesson most men still ignore. You cannot bully sleep into a shape it does not want.

Kleitman spent the rest of his career studying sleep. He published Sleep and Wakefulness in 1939. In 1953, he and Eugene Aserinsky discovered REM sleep, the stage where most dreaming happens. Many researchers call him a father of modern sleep science. Kleitman died in 1999 at the age of 104.

You can learn from a man who gave his whole working life to sleep. Respect your body's clock, and it will look after you. Kleitman gave his clock a century of respect.

THIS “canned food” is linked to Memory Loss

Have you been a little more forgetful lately?

Misplacing things… forgetting names… walking into a room and blanking?

Most people brush it off as “just getting older.”

But new MIT research suggests something else might be going on.

They found that one common canned food contains a “sticky toxin” that may be linked to memory loss in seniors.

This brain-killing toxin can CHOKE your neurons to death – erasing precious memories as you sleep.

So…

Can you guess which canned food is silently killing your memory?

The answer will shock you…

Because it's likely sitting in your kitchen pantries right now:

>> Click here to see which “canned food” is KILLING your memory (before it's too late).

THE NIGHT SHIFT YOU CANCEL

You treat sleep like the gap between days. One more episode wins most nights, and the alarm stays early anyway. Coffee is supposed to cover the difference.

You may even brag about getting by on five or six hours. Plenty of men do. Your brain keeps a different ledger.

I used to think the same way. Then I read what the brain actually does while you are out. Sleep is not downtime for your head. It is the cleaning shift.

You probably feel the cost already. The name that will not come, the second cup at ten, and the short fuse in traffic can all be the bill for short nights.

WHAT HAPPENS AFTER LIGHTS OUT

You have three jobs going on up there while you sleep. I will take them in order.

01 / The rinse

University of Rochester researchers studied this in mice and published it in Science in 2013. During sleep, the space between brain cells grew by about 60 percent. Fluid moved through faster and carried away beta-amyloid, a waste protein linked to Alzheimer's disease.

02 / The cost of one bad night

NIH scientists kept 20 healthy adults awake for one night in a 2018 study. Brain scans the next morning showed beta-amyloid up by about 5 percent, including in the hippocampus, a memory center. The volunteers ranged in age from 22 to 72.

03 / The filing

You also sort the day's memories while you sleep. Kleitman's discovery of REM opened up that whole field of research. Scientists now link deep sleep and REM to moving new memories into long-term storage.

PROTECT THE SHIFT TONIGHT

You can start by picking a wake time and keeping it, weekends included. A steady wake time anchors the same clock Kleitman could never trick. Bedtime tends to follow on its own.

You can also get outside in the morning light. Ten minutes of daylight helps set the clock for that night.

You can also stop the caffeine after lunch. Coffee can keep working in your system for hours after the cup is empty. That late cup may be costing you the deepest part of the night.

You can make the bedroom dark and cool. Blackout curtains and a cheap fan do more than you would think.

You should go easy on the nightcap. Alcohol may knock you out faster, but it is linked to lighter, broken sleep later in the night.

I would leave the phone on the kitchen counter overnight. The news will still be there in the morning, along with your messages.

I would also take snoring seriously. If your wife says you stop breathing at night, tell your doctor. Sleep apnea breaks up the very sleep your brain needs to clean house.

You are not being lazy when you go to bed on time. Your brain simply needs the crew to finish its work.

One last thing. Your brain does its housekeeping in the dark. Give it the full shift.

— Travis

Insider Member's Corner

6 free habits that protect the night shift:

You didn't put in 45 years to settle for beige.

01 / Experience · A Night at the Icehotel

The Icehotel in Jukkasjärvi, Sweden, first opened in 1990. Builders cut ice from the Torne River and rebuild the whole place every winter. The rooms hold at about minus 5 Celsius. A permanent building, Icehotel 365, now stands beside the seasonal one. Book one night in an ice room, then go looking for the northern lights.

02 / Book · Shōgun by James Clavell

James Clavell published Shōgun in 1975. The hero, an English navigator named Blackthorne, is based on the real William Adams. FX turned it into a 2024 series that won 18 Emmys, a record for a single season of television. Read the novel on long winter nights. You will put the phone down for it.

03 / Watch · Citizen Promaster Diver Eco-Drive

Citizen's Promaster Diver runs on Eco-Drive, so light charges it and you never change a battery. The BN0150 is rated to 200 meters and wears a 44mm case. Citizen lists it at $450. Leave it on the nightstand, and it will be ready before you are.