By 1930 Most American Homes Had Electric Light

Sleep Before That Gets Described As Longer

Those Descriptions Come From Diaries And Court Records

Nobody In Them Wrote Down How Long They Slept

Counting Sleep Hours Only Started Around 1900

Researchers Put Wrist Monitors On Three Groups In 2015

They Slept Six Point Four Hours A Night On Average

This Part Covers What Researchers Actually Found

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OKAY BACK FROM THE FACTORY FLOOR 🏭

Thomas Edison Called Sleep A Waste Of Time

He Repeated That Line In Interviews For Years

His Stated Figure Was Four Hours A Night

Contemporaries Reported He Napped Through The Day

He Kept Cots In His Labs And His Library

His Four Hour Figure Never Counted Those Naps

Nobody Ever Timed His Sleep

He Called People Who Slept Longer Inefficient

Electric Light Was The Product He Sold

Customers Who Stayed Up Used More Of It

Factory Owners Wanted Longer Working Hours

Machines That Stopped At Night Made No Money

Shift Work Kept Them Running After Dark

Gas Lamps Had Already Lit Those Factories

Electric Bulbs Lit Them More Safely

Employers Counted Rest As Lost Output

Sleeping Late Got Called Laziness

Waking Early Got Called Discipline

Neither Label Came From Any Measurement

People Still Use Both Labels Today

Roger Ekirch Spent Years In European Archives

Court Records And Diaries Mentioned A First Sleep

The Same Documents Mentioned A Second Sleep

People Woke For An Hour Between Them

They Prayed Or Talked Or Lay Awake

Ekirch Published The Finding In 2001

Writers Kept Mentioning It Into The Late 1800s

By 1900 They Had Stopped

Artificial Light Reached Homes Over The Same Years

That Timing Is Why Historians Connect The Two

A Match In Timing Is Not Proof Of Cause

There Is A Second Problem With The Diaries

Literate Europeans Wrote Almost All Of Them

Nobody Kept Diaries Across Most Of The World

One Region Does Not Prove A Human Pattern

Ekirch Documented That Segmented Sleep Existed

Nobody Documented That It Was Universal

Those Two Claims Are Not The Same Thing

Most Retellings Report Only The Second

The Archives Never Showed That

Niall Boyce Challenged The Evidence In 2023

Ekirch Answered With Two Hundred More Sources

Gandhi Yetish Led A Study Published In 2015

Three Groups Wore Monitors On Their Wrists

The Hadza Live In Northern Tanzania

San Communities Live In Namibia

The Tsimane Live In Bolivia

None Of Them Have Electric Light At Home

The Shortest Group Slept Five Point Seven Hours

Seven Point One Was The Longest

The Average Came To Six Point Four

Industrial Societies Sleep About The Same Or More

Sleep Began About Three Hours After Sunset

Nobody Went To Bed When The Sun Did

They Stayed Awake Well Past Dark

Temperature Predicted Their Timing Better Than Light

Winter Nights Added About An Hour Of Sleep

Researchers Found No Segmented Sleeping In Any Group

Not One Group Woke For An Hour In The Night

Three Groups Cannot Answer The Whole Question

They Still Contradict One Specific Claim

Nobody Has Measured A Past With Longer Nights

That Claim Comes From Writing And Not Data