Sanaa, Yemen (CNN) Noon in the Yemen. A sullen hour with the sun at its scorching zenith, the entire country is tense, on the verge of a national itch. When matters of war, and near-famine, fade to irrelevance.

Relief comes in a pink plastic bag filled with narcotic twigs that 90% of Yemeni men, and 70% of women, cram into their cheeks.

Happiness here is a lump of green mush the size of a tennis ball that's masticated in public.

There's no shame attached to getting high on khat. Its effects have been likened to amphetamines. It tastes like grassy banana skin.

Khat has replaced coffee, wheat and other crops across Yemen.

These figures for consumption of khat aren't guesses, they're government estimates, underpinned by the World Health Organization in 2008 , which also notes that 15-20% of children under 12 also chew the drug.

The Ministry of Agriculture further reckons that a third of agricultural land and a third of water for farming is taken up with growing the drug.

Many officials believe that these figures may be woefully low -- some studies, cited by the United Nations, suggest that 60% of Yemen's farmland is given over to khat.

Khat grows in the mountains of Yemen.

And anecdotally, on a 2,500-mile (4,000km) drive around the Houthi-held north of the country, which is divided by civil war, it is very clear that khat (Catha Edulis) is the region's preferred crop.

Which is odd when one considers that the UN's World Food Programme estimates that it will have to feed 12 million Yemenis this year. Before the latest round of conflict blew up four years ago, the WFP fed a million.

Even khat dealers think that it's silly for a nation, which is dangerously short of food, to be growing an inedible narcotic.

Mohammed Sulwei is acknowledged by fellow khat dealers in Sanaa, as the purveyor of the main drug market's finest inebriant.

A pink bag weighing about a pound and a half of the best hedge-like twigs, brought in daily, goes for 25,000 Yemeni riyals, that's about $50.

Khat dealer Mohammed Sulwei sells at the top end, but even he agrees it makes no sense for people to buy drugs instead of food.

The cheapest khat he sells goes for $5 a bag, although the lowest quality fetches about $2.50 elsewhere. That's at least enough money to buy food for a family of seven for a day.

I ask him: "Do you think that it makes sense for Yemen, that has no food, for everybody to be chewing?"

He replied: "No." And went on to say that he'd have no problem if the drug was banned. "I'd sell something else," he said.

Nearby, Hussein al Jebri guides a gleaming silver 4x4 through a growing crowd of khat buyers haggling with salesmen who dispense their drugs from elevated stalls.

Young and old frequent the market stalls selling khat in the capital, Sanaa.

He's buying, he says, not for himself but for his workers.

"Actually, they are escaping away from normal life. You know we are at war, and they want a way to feel good. You get me? And some people, they don't care about the money," he explained.

Chewing khat is a traditional and central part of Yemeni life. Afternoons are spent chatting, chewing, and sipping endless small glasses of sugary tea.

As the effects intensify, a sense of clarity takes hold on the user.

According to a study published in the journal Neurosciences : "In the central nervous system khat chewing could manifest itself as moderate degree of euphoria and mild excitement resulting in promotion of social interaction and causing loquacity.

Cheeks bulging with khat are seen everywhere in Yemen. Here, armed supporters of the Houthis chew while at a rally in Sanaa in 2015.

"While attaining a state of subjective well-being, the chewers feel an increase of alertness and energy together with enhanced depth of perception. These effects were found to be maximum between 1.5-3.5 hour after starting of the khat chewing."

But: "They were progressively replaced by mild dysphoria, sedation, anxiety, reactive depression, insomnia and anorexia."

Which explains the noontime heebie-jeebies that grip most of Yemen.

Khat is harvested at dawn and distributed across the entire country by a network of high-speed pickup trucks driven at terrifying speeds so the drug can be brought to market before it wilts. There is no regard for the front lines in the war between the Houthi rebels, who control the capital and much of the northwest, and the Saudi-led coalition of forces that support Yemen's government.

Yemeni men harvest khat on a farm on the outskirts of Sanaa in 2016.

Most places only get it by lunchtime. So the focus of the day for almost every Yemeni is on getting over the morning's downer, getting some food into the belly (khat is agony on an empty stomach) and then settling down for a good chew.

The country is in the grip of a humanitarian crisis. The WFP says it's "one step away" from famine.

In Abs, not far from the Saudi border where fighting has recently intensified sending 10,000 new refugees into flight, malnutrition haunts the camps of displaced thousands.

In the local hospital, children with illnesses are so poorly fed they have little energy to survive. Chest infections and diarrhea threaten to kill stick-thin toddlers and children lying inert attached to drips and feeding tubes.

Outside, the khat trade is brisk. And the acacia trees that pepper the scrubland beyond bloom pink with plastic bags snared in their thorns.

We asked Hussin Al-Ezzi, the deputy foreign minister of the rebel Houthi government: "Why should we, the international community, send food to Yemen -- north and south -- when the whole country is walking around with a drug in their mouth?"

"It is used as a social tradition and has nothing to do with aid. I don't know why you connected khat with aid," he replied.

Hussin Al-Ezzi agreed khat chewing was a bad habit but said people's choice to buy khat not food had nothing to do with Yemen's need for aid.

We pressed on: "It's very simple. Most of your land is given to growing drugs not food."

The minister said: "I agree with you, this is a bad habit that we should get rid of. This is indisputable." But there's no sign that khat cultivation is anything but burgeoning.

Magnificent peaks and ridges thick with woodland loom over Shaneen village, three hours east of Sanaa. Spring water spills out of small holes in the ground and terraces carved over millennia into the landscape are verdant green, choked with khat trees.

Farmers there said that 20 years ago their fields were full of wheat.

Mounir al Rubaii is one of the farmers who depend on khat.

"Khat is the top crop because the market for the others is not good," he said.

Farmer Mounir al Rubaii says khat is the only crop that generates a profit.

"We can only make a profit from khat. Other crops don't cover our home expenses. This is the only crop that would cover our daily and annual expenses."

With the vast majority of Yemenis using the drug, that's not surprising.

But it's an addiction that's being enabled by humanitarian aid. The Yemeni government recently estimated that the khat industry was worth about $12 billion to the country.

That happens to be about three times the amount that the UN says it needs to feed Yemen.