Enlarge / A cuttlefish swims in an aquarium at the Scientific Center of Kuwait on March 20, 2016, in Kuwait City. (credit: YASSER AL-ZAYYAT/AFP via Getty Images )

Young jumping spiders dangle by a thread through the night, in a box, in a lab. Every so often, their legs curl and their spinnerets twitch—and the retinas of their eyes, visible through their translucent exoskeletons, shift back and forth.

“What these spiders are doing seems to be resembling—very closely—REM sleep,” says Daniela Rössler, a behavioral ecologist at the University of Konstanz in Germany. During REM (which stands for rapid eye movement), a sleeping animal’s eyes dart about unpredictably, among other features.

In people, REM is when most dreaming happens, particularly the most vivid dreams. Which leads to an intriguing question. If spiders have REM sleep, might dreams also unfold in their poppy-seed-size brains?

Enlarge / A cup of coffee might provide you some pep, but it won’t fully make up for lost sleep. (credit: iStock / Getty Images Plus )

There is no denying the importance of sleep. Everyone feels better after a good night of sleep, and lack of sleep can have profoundly negative effects on both the body and the brain. So what can be done to substitute for a lack of sleep? Put another way, how can you get less sleep and still perform at your peak?

As a psychologist who studies the ways in which sleep benefits memory, I’m also interested in how sleep deprivation harms memory and cognition. After some initial research on sleep deprivation and false confessions , my students at Michigan State University’s Sleep and Learning Lab and I wanted to see what interventions could reverse the negative effects of sleep deprivation.

We found a simple answer: There is no substitute for sleep.

Enlarge (credit: Imagen Rafael Cosme Daza )

Most creatures sleep, but until now, REM (rapid eye movement) sleep , the phase of sleep in which dreams occur, was thought to be exclusive to vertebrates. Octopuses appear to be the first invertebrates to show they are also capable of this

When it comes to neural function, studies have found these cephalopods are more like us than we think (pun somewhat intended). Having no spine hasn’t stopped them from evolving a complex nervous system. A 2022 study found that parts of their brains, the frontal and vertical lobes, work much like the hippocampus and limbic lobe in humans and other vertebrates. The hippocampus is critical to learning and memory, while the limbic lobe controls complex emotional reactions, such as the fight-or-flight response that is triggered by stress or fear.

Now it seems that octopuses have even more in common with us. In studying their sleep behavior, a team of researchers at the Okinawa Institute of Science and Technology observed both periods of quiet sleep, or NREM sleep (also known as slow wave sleep), and bursts of neural activity, during which the animals’ eyes and tentacles twitched while their skin changed color. Neural activities like these, which are similar to the waking state, only happen during REM sleep. Because they can transition between NREM and REM sleep, octopuses are the only known invertebrates that have two phases of sleep.

Enlarge (credit: Getty | Tim Graham )

An eye-opening analysis of common, over-the-counter sleep aids finds they contain wildly variable amounts of melatonin, with some packing up to 347 percent of the amount on the label.

The study , published Tuesday in JAMA, found that 22 of 25 melatonin gummy products analyzed—88 percent—were inaccurately labeled. That is, they contained over 10 percent more or less melatonin than what was listed on the packaging. Together, the dietary supplement products contained a range of melatonin that spanned 1.3 mg to 13.1 mg per serving. And those actual quantities represented a range of 74 percent to 347 percent of what they were supposed to contain based on their labeling.

The finding highlights a larger concern over the quality, safety, and effectiveness of dietary supplements, which are not vetted or approved by the Food and Drug Administration like over-the-counter medicines, such as ibuprofen and allergy medicines. The multi-billion dollar industry has long shrugged off substantial concerns over quality control, safety , lack of effectiveness data , and hyped health claims .

Enlarge (credit: Jetta Productions )

If you went to high school in the US, you may recall early morning extracurriculars, sleeping through first period algebra, or bleary-eyed late-night study sessions (as opposed to other wide-awake “study sessions” we told our parents we were having). As an adult, you might wonder if there’s a better time to explore Shakespeare than at 8 am, or expand a Taylor series right after you collapsed into your chair, half-asleep from your sunrise bus ride.

As it turns out, early school start times for US high schools are built on a shaky scientific foundation, as journalist and parent Lisa Lewis lays out in her new book, The Sleep-Deprived Teen . She details why high schools in the US tend to start early, the science behind why that’s bad for kids, and how later school start times can benefit not only teenagers, but, well… everyone. Perhaps most importantly, she provides a primer on advocating for change in your community.

The wheels on the bus go round and round

Our early start times are a bit of a historical accident. In the first half of the 20th century, schools tended to be small and local—most students could walk. Lewis points out that in 1950, there were still 60,000 one-room schoolhouses around the country. By 1960, that number had dwindled to around 20,000.

Enlarge / This little guy looks too perky to need a nap. (credit: Tony Liu )

Our sleep is marked by cycles of distinct brain activity. The most well-known of these is probably rapid eye movement, or REM sleep, which is characterized by loss of muscle control leading to twitching and paralysis, along with its eponymous eye movements. REM sleep is widespread in vertebrates, appearing in many mammals and birds; similar periods have also been observed in lizards.

Figuring out what might be going on beyond vertebrates can get a bit challenging, however, as identifying what constitutes sleep isn't always clear, and many animals don't have eyes that move in the same way as those of vertebrates. (Flies, for example, must move their entire head to reorient their eyes.) But an international team of researchers identified a group of jumping spiders that can reorient internal portions of their eyes during what appears to be sleep.

And according to this team, the spiders experience all the hallmarks of REM sleep, with periods of rapid eye movements associated with muscle twitching.