Carla Zeus and this is your 10 minutes down the middle explanation of World News, a CNN 10.

Our first story this Wednesday examines how oil tankers are functioning, like chess pieces in global strains involving the United States in the Middle Eastern nation of Iran.

Last year, the Trump administration pulled the US out of a controversial nuclear deal concerning Iran.

The international agreement had been made in 2015 under the Obama administration, and while its supporters said it would put a pause on Iran's efforts to build a nuclear weapon, its critics said it didn't go far enough to stop Iran's nuclear ambitions.

Before the deal was made, the U.

S had sanctions in place penalties on Iran that hurt the Middle Eastern nations economy.

When the U.

S.

Left the deal last year, those sanctions were put back in place, and they're once again taking a toll on Iran.

The two countries have been threatening each other since then, one of the latest incidents involved in Iranian oil tanker that was seized in Gibraltar last month.

This is a British territory in southern Spain.

Authorities stopped the Iranian ship because they thought its cargo was headed somewhere illegal under European rules.

Iran said it wasn't.

And two weeks after its ship was seized, Iran stopped a British flagged tanker that it says was sailing the wrong route in the Middle East.

Iran's government says this had no connection to Gibraltar, but international observers think it was an act of revenge.

Earlier this week, Gibraltar released the Iranian ship after Iran and the owners of the ship's oil promised it wouldn't be taken anywhere.

It wasn't supposed to go, but the U.

S stepped in and tried to block the ship from sailing.

The American government says it believes the ship was helping Iran's Revolutionary Guard Corps, part of Iran's government, that the U.

S has labeled a foreign terrorist organization.

European leaders haven't labeled the Revolutionary Guard Corps a terrorist group, so they went ahead and let it go.

But what happens next?

What about the British ship that Iran seized in the Middle East?

Claressa Ward explains the importance of the Strait of Hormuz.

We're here on Iran's southern coast, right on the Strait of Hormuz, and this is a vitally important passage point for nearly 1/3 of the world's crude oil and a lot of eyes are right now here on this port city of Bandar Abbas because it is here that a British tanker that was seized in late July is still being held.

A lot of people now waiting to see if that tanker might be released after authorities in Gibraltar finally released an Iranian tanker that they have been holding.

But more broadly speaking, this is a hugely important strategic spot for the Iranians because if Iran can stop the flow of crude oil here in the Strait of poor moves that has massive consequences for the world's oil prices and that is felt across the globe, that potentially gives Iran leverage at the negotiating table as this country continues to chafe under the weight of US sanctions.

Claressa Ward, CNN BANDAR Abbas, Iran social media company Twitter says it's not going to allow any more advertisements from government controlled media outlets like what you'd find in China.

Twitter said Monday it had identified a network of more than 900 accounts that originated in China and tried to stir up political trouble in Hong Kong, in part by attempting to weaken the protest movement.

We covered that story in depth on yesterday's show.

You can find it in our archives.

At CNN Tenn dot com, government controlled media outlets will still be allowed to post on Twitter.

They just can't advertise on it.

China says it's reasonable that Chinese media use social media to communicate with locals, tell stories about China and introduced Chinese policies.

This is another facet to the unrest concerning Hong Kong in mainland China, and the tensions between them are palpable at their border.

It's over the past several weeks, we've heard a lot of anecdotal evidence from friends, other journalists that here at the mainland China Hong Kong border, it's actually harder to get across.

There's a lot more security checks.

People have had their phones, check their laptops check.

So we wanted to see for ourselves what's going on.

The speculation amongst travelers we spoke to is that any increased border security is related to the months of violent protests in Hong Kong.

We saw security changes right away.

This is our camera being temporarily detained by police while crossing the border.

So we just made it through the first border checkpoint into Hong Kong and our camera woman, Natalie, was detained and questioned for roughly 40 minutes.

The officer specifically said it had nothing to do with Hong Kong, and then it was random.

But in her nine years as a journalist in China, that is the first time that she's ever been questioned at a border checkpoint.

From there we went to the West Calhoun train station, a key cross border transportation hub, asking people about the security situation.

There was difficult.

We tried to speak to more than two dozen people about the border, and not one of them agreed to go on camera.

And in my experience, I'm not surprised.

They were nervous to talk about something so sensitive to Chinese authorities.

Seven people did speak to us off camera, though all frequent travelers across the border, they said security had increased.

All have had their phone searched, and one woman who'd attended a protest said officers erased videos from that day, and all said these measures only started after the protests began, which we experienced ourselves on the way back to China.

So we just made it through mainland China immigration.

We're now on the train back to sh engine, and it was not an easy process the team was questioned and detained for the better part of an hour, We were asked why we were in Hong Kong.

What stories were we doing there?

Why were we going back to mainland China?

One of the team members?

Actually, I was given a full body search.

And you know, this just doesn't usually happen when you enter and exit China.

We weren't the only ones facing increased scrutiny.

In fact, we saw mainland Chinese and Hong Kongers after going through immigration, being asked to re verify their identification, and some of them even had their phone searched.

CNN asked the Public Security Bureau for comment but didn't hear back.

Multiple officers on the ground told us the searches were random and not connected to the protests.

But look, immigration officers searching phones at borders or increasing security because of social unrest is not unusual.

But the fact is, the Hong Kong China border is farm or on edge.

As Hong Kong's summer of descent continues.

Matt Rivers, CNN Shengjun.

In 18 83 Warren Johnson received a patent for what invention?

Electric thermostat, typewriter, vacuum cleaner or ballpoint pen.

The namesake of Johnson Controls got a patent for the first electric thermostat.

There is no debate that it takes energy to run your air conditioner in the summer heat and raises your electric bill to lower the temperature.

But there is a debate taking place over what the best temperatures are when you're at home.

Energy Star, a U.

S government program that aims to help Americans save energy, recommends that the coolest you should keep your house during the day is 78 degrees.

It also recommends turning on the ceiling fan that doing that can make the room feel four degrees cooler.

Now people can debate all day long about what the most comfortable temperature is, whether 78 would work for them with or without a fan.

And that's just whatever's comfortable for you.

But here's where things get a little controversial, energy star says.

When you're asleep, if you want to save energy, you should keep the temperature at 82 degrees.

There's a big difference between that and what's recommended by the National Sleep Foundation.

It says the best temperature for sleeping is between 60 and 67 degrees.

That this helps your body cool off to fall asleep and stay that way.

Of course, the two different organizations have two different priorities.

One being saving energy and money and the other being getting better sleep well.

There's certainly no one right answer for every person.

The guidelines of 60 degrees at the low end and 82 degrees at the high end, along with the electric bills they bring, could help you determine what's best for your body and your budget.

When air mattresses go Airborne tended to 10 at a movie under the Stars event in Colorado, People brought the air mattresses to relax on, but then a storm blew up and a man swimming in a nearby, Poole said mattresses began blowing in over the fence.

He grabbed his camera and captured what one observer called the great mattress migration of 2019.

What witnesses say looked like between 50 and 100 beds tumbling like tumbleweeds across the land.

Glad he was able to inter spring in the action and keep an even temper with the material.

It might make some plush, but you'd never get headboard of watching it.

The video is framed well and made a dream like memory from the air.