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Unlimited slows. Hey,

0:36

guys, I'm Nate, and this here

0:38

is Curiosity Daily from Discovery, the best place to

0:41

get smarter in just a few quick minutes. Thank

0:43

you so much for joining us here today at

0:46

Curiosity. I'm Callie. Today, you'll learn

0:48

about how microgravity affects sleep

0:50

and physiological rhythms, the half

0:52

a billion year old bioluminescent

0:55

octocoral, and the truth

0:57

about women's synchronized menstrual cycles. All

0:59

right, let's get started. Researchers

1:01

from the University of Surrey in England

1:03

worked with the European Space Agency to

1:05

figure out how microgravity affects our sleep

1:07

patterns and biological rhythms. And

1:10

the findings suggest we've got our work cut out for us

1:12

if we ever hope to wander the solar system. So

1:15

we've talked about the effect of microgravity on

1:17

our muscles and other biological systems. How is

1:19

this study different? Oh, that's a

1:21

great question. I mean, it's no secret that we've

1:23

adapted to thrive in Earth's gravity and that microgravity

1:25

can cause all kinds of chaos on our bodies.

1:29

Previous studies have shown that microgravity can cause

1:31

immune suppression, pump up your inflammation levels, and

1:33

reduce your muscle and bone density. But this

1:36

study focused more on biorhythms. Like

1:39

the sleep cycle or circadian rhythms, that

1:41

sort of thing? Right. The primary

1:43

goal was to examine changes in

1:45

sleep patterns, biological rhythms like body

1:47

temp, activity, and sleepiness, and also

1:49

take a deep look at physiological

1:51

responses under simulated microgravity. Wait, simulated

1:54

microgravity? How do you simulate microgravity?

1:57

That's one of the most interesting parts of the study. So

2:00

it was conducted at a space clinic

2:02

where 20 male participants underwent a 90

2:05

day protocol. It's pretty intense. So for

2:07

two weeks, researchers took baseline measurements of

2:09

those things they wanted to observe. So

2:12

like sleepiness, sleep patterns, biorhythms, body temp,

2:14

all that. Exactly. So two weeks of

2:16

observation just to get a sense of

2:19

their starting point. And then 60 days

2:21

of constant bed rest with a six

2:23

degree head down tilt to simulate microgravity.

2:26

Geez, 60 days of bed rest with heads

2:29

tilted down. That sounds like torture. And it's definitely

2:31

not for the faint of heart. I should say

2:33

so. Uh, but

2:35

is it a good stand in for microgravity? I

2:37

mean, you still feel the effects of gravity pulling

2:39

you downward. It's just that your head

2:41

is aimed down. Does that work? Apparently

2:44

it's a good stand in for microgravity. It's been

2:46

used in some of the previous studies that found

2:48

the effects of microgravity on bone density and muscle

2:51

mass that we talked about. And

2:53

it's helpful because in the case of

2:55

actual astronauts, it's not super easy to

2:57

conduct consistent experiments like this while they're

2:59

working in space. Either the data

3:01

is hard to standardize or they're just not in

3:03

space long enough. So head down tilt

3:05

it is. All right. How does

3:07

microgravity affect our sleep? Well,

3:10

let's just say it doesn't help it.

3:12

There was a noticeable decrease in temperature

3:14

activity and sleepiness rhythms. Mass spells fairly

3:16

significant changes. For example, the participants didn't

3:18

sleep as well at night, only clocking

3:20

in about 6.5 hours,

3:23

but their daytime napping increased.

3:25

It sounds like the rhythm was basically

3:27

just thrown off. It threw off

3:29

their groove. Anyways, they also

3:32

found that the relationship between skin temperature

3:34

and sleep stages was disrupted. So the

3:36

way that our temps rise and fall

3:38

with our sleep was also just not

3:40

right. So of course, disrupted sleep

3:42

already seems to have an impact on things

3:44

like inflammation, right? So the bone

3:46

density loss, the muscle loss, the inflammation from the

3:49

other studies, all of that

3:51

stuff isn't exactly helped by disruptive

3:53

sleep. Mmm, not exactly. It's

3:56

not surprising that these disruptions could lead

3:58

to pretty significant health and performance issues.

4:00

for astronauts, especially on long-hauls

4:02

to have planets. But simply

4:04

knowing these effects gives researchers a jump

4:06

on creating strategies to counter them, and

4:08

that's the key. So does this study

4:11

also tell us anything about bedrest? Seems

4:13

like you could draw some conclusions from that as

4:15

well. Oh, totally. The researchers say

4:18

that the findings are totally relevant for

4:20

understanding the effects of long-term bedrest here

4:22

on Earth, which could impact future studies

4:24

on aging and chronic illness treatments. This

4:28

is the ability of living things to produce and

4:30

emit light. And while it's fairly

4:32

rare on land, by some estimates as many as

4:34

80% of marine organisms

4:36

in the pelagic zone are bioluminescent.

4:39

And the pelagic zone is that area that's kind of in

4:42

the middle of the depths of the sea. It's not too

4:44

shallow and it's not too deep, right? Yeah,

4:46

basically. It's between around 600

4:48

feet and 3,200 feet below the surface. I

4:53

didn't realize so many of the creatures and organisms

4:55

in the pelagic zone were bioluminescent. Yeah,

4:57

I didn't either. It turns out the

4:59

sea is full of light, albeit mostly

5:01

tiny blue lights. But

5:03

that bioluminescence has piqued the

5:06

curiosity of marine biologists for

5:08

about as long as there have been marine biologists. And

5:11

among the most pressing questions they ask, how

5:14

and why and when did organisms first start lighting

5:16

up? Well, a new study

5:18

is suggesting that it started a long

5:21

time earlier than researchers ever thought, like

5:23

hundreds of millions of years earlier. Whoa,

5:25

okay, so why? I mean, I assume

5:27

there's some kind of evolutionary advantage to

5:30

being able to emit light, but when

5:32

did it happen? Well, that's

5:34

a great question. So researchers had previously

5:36

found evidence of bioluminescence in 267 million

5:38

year old sea

5:41

fireflies. But this

5:43

research team analyzed the DNA of

5:45

185 different species of octocorals, that

5:48

includes soft corals, sea pens, sea fans,

5:50

all sorts of corals that all have

5:52

eightfold symmetry. And using their

5:55

DNA analysis, they were able to construct

5:57

an evolutionary tree to piece together the

5:59

genetic relationship among all these species. So

6:02

if you could see how they were all related, you'd

6:04

have some sense of their common ancestry, is that right?

6:07

Yeah, that's basically right. After all

6:09

the analysis and puzzle piecing, they

6:12

were able to estimate the timing

6:14

of evolutionary splits and calculate the

6:16

likelihood of ancestral species being bioluminescent.

6:18

I mean, this is kind of like a 250 million

6:20

year old puzzle. I mean,

6:22

piecing all that together is kind of mind

6:24

boggling. Try 540 million year old puzzle. Hey,

6:29

wait half a billion years. Yep.

6:31

This study pushes the probable timeline

6:33

for the origin of bioluminescence in

6:35

these corals to 540 million years

6:37

ago. Do the math and you

6:39

can see that it pushes back the origin

6:41

by some 300 million years. All

6:43

right. So here's kind of a basic

6:45

question. How does bioluminescence work? Right.

6:48

So bioluminescence happens because of a

6:50

chemical reaction between the organism and

6:53

a compound in the environment. And

6:55

that's one of the more interesting things

6:57

here. Different forms of bioluminescent life depend

6:59

on different chemical reactions to make them

7:01

light up, which suggests that

7:04

this ability probably evolved independently

7:07

dozens, if not hundreds of times.

7:10

Oh, okay. So in other words, there's

7:12

not just one single common bioluminescent organism

7:14

that all of these other creatures came

7:16

from. No, the researchers also say that

7:18

this ability is pretty unique in that

7:20

it seems to evolve into existence pretty

7:22

easily, but it also evolves

7:24

out pretty easily. That means that

7:26

the history of bioluminescence is really

7:29

complicated and suggests that this study

7:31

may have only discovered the earliest

7:33

known example of bioluminescence. Oh,

7:35

so there could still be some older examples out

7:38

there just waiting to be found. Yes. Although

7:40

at half a billion years old, the fossil

7:42

record isn't exactly easy to sift through. So

7:45

while creatures could have been lighting up the

7:47

ancient seas longer than 540 million years ago,

7:50

we may never actually know for sure. Neat.

7:54

I like the ocean. Hey,

7:58

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limited time. Unlimited more than 40 gigabytes per month, slows. Full terms

8:27

at mintmobile.com. Most

8:31

of us have probably heard the story of the

8:33

sorority house or the girls dorm where all of

8:36

the women ended up having their periods at the

8:38

same time. Yeah, I've definitely heard about it. As

8:41

I understand it has something to do

8:43

with pheromones or hormones, right? Yeah, it's

8:45

called the McClintock effect after a

8:47

psychologist named Martha K. McClintock. In

8:50

1971, she conducted a study with 135

8:53

women in a college dorm and observed

8:55

that their menstrual cycles seemed to synchronize

8:57

over time. She thought it might

8:59

have something to do with their social interactions.

9:01

I mean, maybe there was a physiological process

9:03

at play and maybe influenced by pheromones, like

9:05

you mentioned. That is really

9:07

fascinating. So, if there's a physiological

9:09

process at play, what is

9:12

the evolutionary advantage of synced menstrual cycles?

9:14

Okay, so I'm glad you asked because

9:17

there is absolutely no advantage. A

9:19

synchronized menstrual cycle would imply that women

9:21

who are close socially are fertile at

9:23

similar times. And there's just

9:25

no known advantage for all of the women

9:27

in a clan or tribe being pregnant at

9:29

the same time. I mean, in fact, that

9:31

could actually be a bad thing given a

9:33

finite amount of resources, right? Yeah,

9:36

yeah, okay. So, why do

9:38

women who live together have synced cycles? Okay,

9:40

so the short answer? They probably don't.

9:43

Wait, what? What

9:45

about the McClintock effect in the 1971 study?

9:48

I feel like I've heard stories from friends who this

9:51

happened to. How could it not be real? So,

9:53

several studies that were conducted in the more

9:55

recent past have found that the answer likely

9:57

lies in math. Mm, I think you

9:59

lost. Okay, let me give you

10:02

an example. A research team in Israel conducted

10:04

somewhere around 15 different studies on this in

10:06

the 1990s and found that the

10:08

women they observed were in sync... sometimes. And

10:11

sometimes they weren't. In other words, the

10:13

synchronization was a mathematical coincidence. Wait,

10:16

like... Okay, I see. If you

10:18

get several women together living in close proximity, some

10:21

of them may have overlapping cycles, something like that. Sure,

10:24

but add to that the fact that women

10:26

have varying menstrual cycles. So, imagine a solar

10:28

eclipse. The moon, the earth,

10:30

and the sun all move at their own pace. But

10:33

every once in a while they line up. It doesn't

10:35

mean that they're synchronized, just that their motion happens to

10:37

overlap every once in a while. Okay,

10:40

so there's no such thing as menstrual synchrony.

10:43

But if it doesn't exist, how did we ever come up with

10:45

it in the first place? I

10:47

mean, it's partially because of that overlap.

10:49

It's a shared experience, and women's menstrual

10:51

cycle isn't something that is historically celebrated,

10:53

right? So when you're

10:55

going through something with your close friend or sister

10:57

or mom, it can feel empowering. Okay, that's

10:59

a great point. And we tend to believe

11:02

things that make us feel empowered. Yeah,

11:05

and it's also worth noting that Dr.

11:07

McClintock, who has shifted her own views

11:09

on this since the 1971 study, still

11:11

believes that synchrony is a real thing,

11:13

but is more in tune with ovulation

11:15

times rather than menstruation. She

11:17

believes pheromones are the culprit, but her theories

11:19

are still controversial. So

11:22

it's possible. I mean,

11:24

it's possible, but at least according to a lot of

11:26

newer research, not likely. But that

11:28

shouldn't keep women from forming bonds of solidarity

11:30

in any manner they see fit. Like

11:33

when we all decided that we were going to listen

11:35

to True Crime podcast, like women think about murder as

11:37

much as men think about the Roman Empire. Okay,

11:40

okay. Let's

11:44

recap what we learned today to wrap up. Simulated

11:47

microgravity significantly disrupts sleep and biological

11:49

rhythms, which could impact astronaut health

11:51

and performance in space. The

11:54

eerie glow of bioluminescence in corals may

11:56

have begun over 540 million years ago.

12:00

doubling the previously known age of this

12:02

luminous trait. Despite long-held beliefs,

12:05

menstrual synchrony among women who live

12:07

together is likely a myth, with

12:09

studies suggesting that an observed synchronization

12:11

is due to statistical coincidence rather

12:14

than biological processes. Curiosity

12:17

Daily is produced by Wheelhouse DNA for Discovery.

12:19

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