6 Hours Of Sleep Per Night Is OK??? Plus How To Sleep Like A Caveman (Wisdom From Our Ancestors For A Better Night's Sleep!) With Dr. Merijn van de Laar

Ben Greenfield

Aug 21, 2025

Episode description

I’m always on the lookout for a good book on sleep, and I recently read one of the better titles I’ve found in the past few years:

How to Sleep Like a Caveman: Ancient Wisdom for a Better Night's Rest—Based on the Evolutionary Science of Sleep from Saber-Toothed Tigers to Modern Insomnia.

Written by today’s podcast guest, Dr. Merijn van de Laar, one of the world’s leading sleep scientists, it is a bit like Sapiens meets Why We Sleep in an evolutionary romp through the science of sleep—and how you can get better rest.

If you’re curious about the science of sleep, what our evolutionary past can teach you, and actionable ways to wake up truly rested, this episode is for you.

Full show notes: https://bengreenfieldlife.com/cavemansleep

Episode Sponsors:

CAROL Bike: The science is clear—CAROL Bike is your ticket to a healthier, more vibrant life. And for a limited time, you can get $100 off yours with the code BEN. Don't wait any longer, join over 25,000 riders and visit carolbike.com/ben today.

Gameday Men’s Health: Gameday Men's Health offers science-backed, physician-led men's health optimization with personalized protocols for testosterone, peptide therapy, ED treatment, and more—helping you perform at your best whether you're training hard or keeping up with life. Visit gamedaymenshealth.com/bengreenfield for a free testosterone test and consultation at a clinic near you.

Just Thrive: For a limited time, you can save 20% off a 90-day bottle of Just Thrive Probiotic and Just Calm at justthrivehealth.com/ben with promo code BEN. That’s like getting a month for FREE—take control today with Just Thrive!

Calroy: Head on over to calroy.com/ben and save over $50 when you purchase the Vascanox (a breakthrough product providing nitric oxide support for up to 24 hours with a single dose) and Arterosil (a premier supplement to support the endothelial glycocalyx—the fragile inner lining of the entire vascular system) bundle at calroy.com/ben. Plus, you'll receive a free canister of 2-in-1 Nitric Oxide Test Strips with a 3-pack bundle purchase.

Ketone-IQ : Ketone-IQ delivers science-backed performance fuel that increases power output by 19%, reduces fatigue by 10%, and naturally boosts EPO production for better oxygen delivery—trusted by elite athletes like Jon Jones and Olympic champ

Mindsip insights from this episode:

Challenge the eight-hour sleep myth for better rest

The belief in needing eight hours of sleep is a social construct, not a scientific mandate, as most people in Western societies actually sleep closer to seven hours.

#sleep

Leverage bizarre dreams to boost brain flexibility

The bizarreness of dreams functions to make our brains more creative and flexible, a theory supported by research showing that making AI systems 'dream' makes them more intelligent.

#cognition

#creativity

Understand hypnic jerks as an evolutionary reflex

The twitching sensation or feeling of falling as you drift off to sleep, known as a hypnic jerk, may be an evolutionary reflex to prevent our ancestors from falling out of trees.

#evolution

#sleep

Utilize orgasm as a natural sleep aid

Having an orgasm, whether with a partner or through masturbation, is a sleep-promoting activity due to the release of hormones and can help you fall back asleep if you wake up at night.

#orgasm

#sleep

Shift bedtime forward to correct delayed sleep phase syndrome

For those with severely delayed sleep phase syndrome, a counter-intuitive but effective method is to shift bedtime forward by three hours each day until the desired rhythm is achieved.

#sleep

Avoid napping to improve nighttime sleep for insomnia

While beneficial for good sleepers, napping can worsen nighttime sleep for individuals with insomnia by decreasing their built-up sleep drive.

#insomnia

#sleep

Accept nighttime wakefulness as a normal trait

Being awake for up to 20% of the night is a normal, evolutionarily advantageous trait, and worrying about it can be more harmful than the wakefulness itself.

#sleep

Prioritize sleep separately to enhance relationship stability

Prioritizing sleep by sleeping separately from a disruptive partner can make you a more attractive and stable partner, ultimately strengthening the relationship.