Science Says Sleeping in a Really Dark Room Will Make You Smarter

The darker the room tonight, the smarter and more alert you’ll be tomorrow. 

EXPERT OPINION BY JEFF HADEN @JEFF_HADEN

Nov 23, 2025

 

 

 You probably already know you need at least seven hours of sleep a night to function at your best. (And don’t say, “Not me. I do just fine on five or six hours.” According to a study published in Cell Research, only a tiny fraction of the population functions well on less than seven hours.)

Why? A 2018 study published in Sleep says if you only sleep for five to six hours you’re 19 percent less productive than people who regularly sleep for seven to eight hours. If you only sleep five hours a night? You’re nearly 30 percent less productive.

That’s especially true for entrepreneurs: A study published in Entrepreneurship Theory and Practice found that lack of sleep makes people more likely to start a business on impulse or whim rather than on a solid, well-considered idea. More broadly, a study published in Journal of Business Venturing found that lack of sleep causes you to come up with worse ideas.

And to believe your bad ideas are actually good ideas. ​

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So, yeah: Getting enough sleep is actually a competitive advantage.

Especially if you take it one step further. According to a 2022 study published in Sleep, sleeping in as close to total darkness as possible can not only improve the quality of your sleep, it can also improve your memory and alertness. 

After just two nights of wearing a sleep mask, participants:

• Displayed significantly better learning skills
• Displayed significantly better physical reaction times
• Learned new motor skills more quickly

Why? One explanation could be the “synaptic homeostasis hypothesis,” the theory that increased slow-wave activity during sleep (which is promoted by darkness) promotes the “down-scaling” of synapses that became saturated while you were awake and restores your capacity for encoding new information. 

Or, in non-researcher-speak, a dark night’s sleep primes both your cognitive and motor skills for the next day. The same holds true for feeling (and actually being) more alert.

That doesn’t mean I’m eager to embrace a sleep mask. It feels weird to have a mask on, and it made me feel like I didn’t sleep as well. But I’m probably wrong; as the researchers write: 

It deserves mention that even though participants reported that sleeping with the control mask was more uncomfortable in comparison with the eye mask, this did not impact self-reported sleep quality, morning alertness, or sleep parameters.

So even if you don’t love the idea of a mask, the mask will still — in terms of the benefits it provides — love you back. 

But you don’t have to wear a mask. Draw your blinds. Consider room-darkening curtains. Turn off device notifications and leave them face-down on your nightstand. The darker you make your bedroom — the more you limit the presence of ambient or intermittent light that can disturb your sleep — the more you’ll benefit in terms of memory performance and alertness the next day.

As the researchers write:

Given the current climate of life-hacking, sleep monitoring, and cognitive enhancers, our findings suggest the eye mask as a simple, economical, and noninvasive way to get more out of a night of sleep.

Source: https://www.inc.com/jeff-haden/science-says-sleeping-in-a-really-dark-room-will-make-you-smarter/91269306 (25/11/2025)

Women less sensitive to pain than men

Women less sensitive to pain than men

For the study, published in the Current Biology journal, the team conducted experiments on both humans and mice where they were taken to specific rooms and made to experience low levels of pain caused by heat delivered to their hind paw or forearm. health Updated: Jan 14, 2019 11:12 IST

Indo Asian News Service

When experiencing pain again, men seemed to be stressed and hypersensitive in remembering, but women were not stressed by their earlier experiences of pain. (Unsplash)

Women tend to forget pain that they suffered more quickly than men, confirmed a new study in mice and humans, challenging the widely held belief that the fairer sex are more sensitive to pain than men. The study, by researchers from Canada’s University of Toronto Mississauga (UTM), showed that men and women remembered earlier painful experiences differently.

When experiencing pain again, men seemed to be stressed and hypersensitive in remembering, but women were not stressed by their earlier experiences of pain.
“If remembered pain is a driving force for chronic pain and we understand how pain is remembered, we may be able to help some sufferers by treating the mechanisms behind the memories directly,” said lead author Loren Martin, Assistant Professor at the UTM.

“What was even more surprising was that men reacted more, because it is well known that women are both more sensitive to pain than men, and that they are also generally more stressed out,” Martin added.

For the study, published in the Current Biology journal, the team conducted experiments on both humans and mice where they were taken to specific rooms and made to experience low levels of pain caused by heat delivered to their hind paw or forearm.

Further, human participants were asked to wear a tightly inflated blood pressure cuff and exercise their arms for 20 minutes, while each mouse received a diluted injection of vinegar designed to cause a stomach ache for about 30 minutes. When the next day the participants returned to either the same or a different room and heat was again applied to their arms or hind paws, men rated the heat pain higher than they did the day before, and higher than the women did.
Similarly, male mice returning to the same environment exhibited a heightened heat pain response, while mice placed in a new and neutral environment did not.

First Published: Jan 14, 2019 11:11 IST

Source: https://www.hindustantimes.com/health/women-less-sensitive-to-pain-than-men/story-BUiLKZderKkA8IA6PcrcQO.html (16.01.2019)

New study finds preference for children to cradle dolls on left is indicator of social cognitive abilities

June 27, 2018 by George Wigmore, City University London

Credit: FamVeld/Shutterstock.com

Children who cradle dolls on the left show higher social cognitive abilities than those who do not, according to new research from City, University of London.

The new findings, which also show deeply inbuilt facial recognition skills which enable children to interpret even simple approximations as human faces, suggest the children's cradling preference could help to indicate some social developmental disorders.
The study builds on previous knowledge of a 'left-cradling bias' – the phenomenon that humans will typically cradle a baby on their left side, enabling both parent and child to keep the other in their left visual field – which is unrelated to dominance of the use of right or left hand. Information from the left visual field is processed by the right hemisphere of the brain, which is associated with emotion and the perception of facial expression.
Further investigation could enable researchers to make important predictions about the trajectory of children's development based on their cradling responses, in association with social and communication abilities.
The research – led by Dr. Gillian Forrester of Birkbeck, University of London and Dr. Brenda Todd of City, University of London – was conducted with 98 typically developing children (54 girls and 44 boys) in reception or year 1 at a mainstream reception school in South London, who were given a human infant doll to cradle.
They were observed to hold the doll markedly more often in a left-cradling position, and those who showed this bias had a significantly higher social ability score compared with those who held the doll on the right.
The social ability traits tested including likeliness to follow rules, willingness to share with others and wanting to please their teachers.
As part of the study the children were also given a pillow to cradle, with three dots marked on to suggest a face. They were more likely to cradle this object on the left, which researchers say indicates the depth of the evolutionary bias, as even a hint of a face will trigger the response.
By contrast, when given a plain pillow, without a suggestion of a face, the children demonstrated neither a left nor right cradling bias.
Birkbeck's Dr. Forrester said: "Even babies recognise the simple design of three dots surrounded by a circle as a face. And faces receive special attention from our left visual field (connected to the right hemisphere), which is faster and more accurate at identifying individuals and their emotional expressions than the right visual field for the majority of the population. This left-visual-field bias is a natural ability, thought to have originated from a need to identify predators in the environment. In modern humans we believe that the left visual field bias for recognising faces and expressions supports our sophisticated social and emotional abilities.

"In our study, children held a plain pillow randomly in either arm, but adding a 'three-dot-face' resulted in a preference to hold in the left arm, mirroring the left-side cradling bias shown by mothers holding babies. The phenomenon, known as the 'left cradling bias', is not just present in humans—it is pervasive across the animal kingdom and found in species as different as gorillas and flying foxes. Keeping a baby in the carer's left visual field allows for more efficiently monitoring of the baby's wellbeing.
"Not surprisingly, the left cradling bias was also seen when children held a human baby doll, indicating that this behaviour is present early in development and you do not need to have had experience of holding babies to express this preference. What was interesting was that children who held the baby doll with a preference for the left arm scored higher on social ability tests, compared with children who held with a right-side preference, indicating that using the visual field linked to the dominant hemisphere for processing social stimuli gives the individual a real-life advantage."
The cradling bias was once thought to be associated with the prevalence of the of the right-handed population but is now known to result from a preference for using the left visual field to view faces – it is quicker and more accurate at identifying individuals and their expressions. Cross cultural studies indicate that approximately 80% of mothers naturally cradle on the left.
City's Dr. Brenda Todd said:
"I have previously studied mothers holding their own babies, finding that the left cradling is strongest in the first 12 weeks after the birth, when the babies are most vulnerable. It is very interesting to see that a similar bias is shown when young children hold a doll which depicts a young infant, indicating that this behavioural preference is apparent so early in our development."

The peer-reviewed study is published in Cortex. 

More information: G.S. Forrester et al. The left cradling bias: An evolutionary facilitator of social cognition?, Cortex (2018). DOI: 10.1016/j.cortex.2018.05.011

Journal reference: Cortex
Provided by: City University London


Source: https://medicalxpress.com/ (28/06/2018)