the presence of jerks during rest in the gray whale, taken together with our previous data on 3 species of dolphins, allows us to suggest that short episodes of REM do exist in Cetaceans

2007-12-27: Orexin A Narcolepsy?

the absence of orexin A appears to cause narcolepsy. That finding pointed to a major role for the peptide’s absence in causing sleepiness. It stood to reason that if the deficit of orexin A makes people sleepy, adding it back into the brain would reduce the effects

2017-06-28: Whale sleep

Franco Banfi was following this pod of sperm whales when the giants suddenly seemed to fall into a vertical slumber. These massive marine mammals spend 7% of their time taking short (6- to 24-minute) rests in this shallow vertical position. Scientists think these brief naps may be the only time the whales sleep.

2017-10-31: Cocaine 2.0

Recent research has demonstrated the effectiveness of short light pulses to alter circadian phase during sleep in human subjects. 2-millisecond light flashes administered during sleep penetrate the eyelids and change circadian timing without interfering with sleep quality. Due to the properties of the retinal cells that transduce light information to the circadian system, these millisecond light flashes match or exceed the effectiveness of continuous bright light to shift circadian phase. More than 1.5 hours of phase shift can be generated with just over 1 total second of light exposure during 1 hour. LumosTech is developing a smart sleep mask that contains bright LEDs able to emit a range of millisecond light pulses at several frequencies. Light timing is controlled by a smartphone app that uses a proprietary algorithm to calculate the frequency and duration required for shifting circadian phase. The light stimulation is delivered during sleep in conjunction with a mathematical model of circadian phase to advance or delay sleep cycles. The mask contains additional LEDs that provide a red-wavelength dawn simulator to stimulate the release of cortisol; this promotes alertness and enhances mood immediately after wakeup.

2018-07-21: What we know about sleep

Our brain profoundly alters its behavior and purpose, dimming our consciousness. For a while, we become almost entirely paralyzed. We can’t even shiver. Our eyes, however, periodically dart about behind closed lids as if seeing, and the tiny muscles in our middle ear, even in silence, move as though hearing. We are sexually stimulated, men and women both, repeatedly. We sometimes believe we can fly. We approach the frontiers of death. We sleep. Around 2.35 ka BP, Aristotle wrote an essay, “On Sleep and Sleeplessness,” wondering just what we were doing and why. For the next 2300 years no one had a good answer. In 1924 German psychiatrist Hans Berger invented the electroencephalograph, which records electrical activity in the brain, and the study of sleep shifted from philosophy to science. It’s only in the past few decades, though, as imaging machines have allowed ever deeper glimpses of the brain’s inner workings, that we’ve approached a convincing answer to Aristotle.

2020-01-04: Sleep detox

An organized tide of brain waves, blood and spinal fluid pulsing through a sleeping brain may flush away neural toxins that cause Alzheimer’s and other diseases.

2020-11-10: Evening home lighting adversely impacts the circadian system and sleep

nearly 50% of homes had bright enough light to suppress melatonin by 50%, but with a wide range of individual responses (0–87% suppression for the average home). Greater evening light relative to an individual’s average was associated with increased wakefulness after bedtime. Homes with energy-efficient lights had 2x the melanopic illuminance of homes with incandescent lighting. Home lighting significantly affects sleep and the circadian system, but the impact of lighting for a specific individual in their home is highly unpredictable.

2021-05-18: Metabolic sleep

What, then, does sleep do in the absence of a brain? Raizen suspects that at least for some animals, sleep has a primarily metabolic function, allowing certain biochemical reactions to take place that can’t happen during waking hours. It may divert the energy that would be used by alertness and movement into other processes, ones that are too costly to take place while the animal is awake. For example, C. elegans seems to use sleep to enable the growth of its body and support the repair of its tissues. In sleep-deprived hydras, the cell divisions that are part of everyday life are paused. Something similar has been seen in the brains of sleep-deprived rats and in fruit flies. Managing the flow of energy may be a central role for sleep.

2021-11-16: Dreaming against overfitting

All of this begs the question of how the human brain deals with overfitting. Our day-to-day experience can be hugely repetitive, so how does the brain generalize from these singular experiences to other situations?

The human brain prevents overfitting by dreaming. Dreaming evolved specifically to deal with this problem, which is common to all neural networks. If this theory is correct, it answers one of the great unsolved problems in neuroscience: why we dream at all.

2022-08-07: Spider REM Sleep?

When Rößler recorded 34 sleeping spiderlings, she found that their twitches were accompanied by unmistakable eye-tube movements that did not happen during other phases of sleep. “It’s beautiful. I mean, it’s crazy. It immediately makes a sleep researcher think about rapid eye movement sleep”. Dreaming offers an entry point into questions of awareness in other animals: it is difficult to imagine that even a simple dream is possible without something like an ego or an “I” experiencing it, he adds. So if spiders dream, it might mean that we start talking about spiders having something like a minimal self.

2023-09-10: REM sleep is body-mapping

The brain uses REM sleep to “learn” the body. You wouldn’t think that the body is something a brain needs to learn, but we aren’t born with maps of our bodies; we can’t be, because our bodies change by the day, and because the body a fetus ends up becoming might differ from the one encoded in its genome. “Infants must learn about the body they have. Not the body they were supposed to have.”

As a human fetus, you have 9 months in a dark womb to figure out your body. If you can identify which motor neurons control which muscles, which body parts connect, and what it feels like to move them in different combinations, you’ll later be able to use your body as a yardstick against which to measure the sensations you encounter outside. It’s easier to sense food in your mouth if you know the feeling of a freely moving tongue; it’s easier to detect a wall in front of you if you know what your extended arm feels like unimpeded. In waking life, we don’t tend to move only a single muscle; even the simple act of swallowing employs some thirty pairs of nerves and muscles working together. Our sleep twitches, by contrast, are exacting and precise; they engage muscles one at a time. Twitches “don’t look anything like waking movements. They allow you to form discrete connections that otherwise would be impossible.”

The theory turned the rationale for REM paralysis on its head: the paralysis isn’t there to stop the twitches but to highlight them. It’s a process that’s most important in infancy, but this might continue throughout our lives, as we grow and shrink, suffer injuries and strokes, make new motor memories and learn new skills. Blumberg plays the drums, and, when he learns a new rhythm, he wonders whether sleep is involved. “You struggle and struggle for several days, then one day you wake up and start playing and boom—it’s automatic. Did sleep play a role in that? If I had been recording my limb movements, would I have seen something interesting? That keeps me up at night.”

2023-10-22: Dream communication

While they were sleeping, participants were repeatedly asked to frown or smile. All of them responded accurately to at least 70% of these prompts.

Overall response rates were higher for all participants during REM (rapid eye movement) sleep, when the deepest sleep occurs but the brain remains quite active, than during other sleep stages.

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