Why We Sleep: Unlocking the Power of Sleep and Dreams

To successfully initiate sleep, as described in chapter 2, your core temperature needs to decrease by 2 to 3 degrees Fahrenheit, or about 1 degree Celsius. For this reason, you will always find it easier to fall asleep in a room that is too cold than too hot, since a room that is too cold is at least dragging your brain and body in the correct (dow

the dreaming brain was not simply recapitulating or re-creating exactly what happened to them in the maze. Rather, the dream algorithm was cherry-picking salient fragments of the prior learning experience, and then attempting to place those new experiences within the back catalog of preexisting knowledge. Like an insightful interviewer, dreaming ta

It is sleep that builds connections between distantly related informational elements that are not obvious in the light of the waking day. Our participants went to bed with disparate pieces of the jigsaw and woke up with the puzzle complete. It is the difference between knowledge (retention of individual facts) and wisdom (knowing what they all mean

The recycle rate of a human being is around sixteen hours. After sixteen hours of being awake, the brain begins to fail. Humans need more than seven hours of sleep each night to maintain cognitive performance. After ten days of just seven hours of sleep, the brain is as dysfunctional as it would be after going without sleep for twenty-four hours. T

During deep NREM sleep specifically, the brain communicates a calming signal to the fight-or-flight sympathetic branch of the body’s nervous system, and does so for long durations of the night. As a result, deep sleep prevents an escalation of this physiological stress that is synonymous with increased blood pressure, heart attack, heart failure, a

The giant insurance company Aetna, which has almost fifty thousand employees, has instituted the option of bonuses for getting more sleep, based on verified sleep-tracker data. As Aetna chairman and CEO Mark Bertolini described, “Being present in the workplace and making better decisions has a lot to do with our business fundamentals.” He further n

Selectively warming the feet and hands by just a small amount (1°F, or about 0.5°C) caused a local swell of blood to these regions, thereby charming heat out of the body’s core, where it had been trapped. The result of all this ingenuity: sleep took hold of the participants in a significantly shorter time, allowing them to fall asleep 20 percent fa

if you don’t sleep the very first night after learning, you lose the chance to consolidate those memories, even if you get lots of “catch-up” sleep thereafter. In terms of memory, then, sleep is not like the bank. You cannot accumulate a debt and hope to pay it off at a later point in time. Sleep for memory consolidation is an all-or-nothing event.

there are four main clusters of the brain that spike in activity when someone starts dreaming in REM sleep: (1) the visuospatial regions at the back of the brain, which enable complex visual perception; (2) the motor cortex, which instigates movement; (3) the hippocampus and surrounding regions that we have spoken about before, which support your a