This Podcast Will Kill You Ep 199 Sleep Part 2: Predictably unpredictable
Jan 27, 2026
They trace how industrialization and artificial light reshaped human sleep and challenge the myth of a single “natural” pattern. Historical accounts of segmented nights, midnight activities, and bedding culture get examined. They highlight wearables, sleep anxiety, and how medical metrics narrowed what counts as normal. The episode ends by weighing public health trends, risks of short or long sleep, and the need for societal flexibility.
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Car Crash From All-Nighters
- Kelly shared falling asleep at the wheel after finals-week all-nighters and totaling her car, Betty.
- She now avoids driving while fatigued and calls the crash a wake-up call.
Segmented Sleep Was Once Normal
- Historical records show biphasic (segmented) sleep was common before industrialization, with a first and second sleep separated by an hour.
- People used the middle-watch for chores, reflection, or socializing rather than panicking about wakefulness.
Humans Are Predictably Unpredictable Sleepers
- Experimental and ethnographic data show human sleep timing is flexible: people stayed up after sunset for social activities and napped when needed.
- This flexibility likely had evolutionary benefits like round-the-clock childcare and creativity at night.
