"We would start taking it on a Friday night and not stop until Sunday – we wouldn’t sleep or eat. By Sunday we were in a state. The comedown started. We couldn’t be alone. We used to curl up in bed or me and my pals on the couch, not speaking just almost in shock. The paranoia kicked-in or as we called, ‘the fear’. It was awful.”

That’s how it started for 28-year-old Rory, who is originally from Dumfreisshire but now lives in Glasgow. He says his addiction to ‘legal highs’ - or Novel Psychoactive Substances (NPS) as they are officially know - began in his final year at university when stressful weeks of studying for a degree in construction management and essay writing were blown away by weekends of clubbing and partying.

"I was studying construction management at uni in Glasgow, I was in my final year and I became addicted to so-called ‘legal highs’. It started with M-cat, which is now banned, my friend bought kilos of the stuff because it was so cheap online and divvied it up between us and we all took it.

"We were all into house music and M-cat went hand in hand with it. It just gave you a feeling of absolute euphoria, it made sounds and colours just pop and come to life but it was f***ing hard coming down."

Rory says he "progressed to buying different combinations online. ‘Burst and ‘Carnage’ and a load of others – they were much cheaper than going out and buying MDMA (ecstasy) from a dealer or coke which I found wasn’t as good anyway.

"While we were on the stuff it was great, I remember running around a casino with my top off getting chased by a security guard, it was insane but we were all having a great time. I lived with a couple of friends who were into taking it; one smoked stuff - cannabinoids and ended in quite a bad way.

"I found myself with a huge bag of powder in my desk drawer and taking it every day, I basically stopped going to classes."

What are they?

Legal highs have been part of the UK drug scene for the past decade but are now increasingly popular with users trying to avoid the risk of a criminal record that comes using traditional drugs like cannabis, speed, cocaine, ecstasy and LSD. NPS have been implicated in 62 deaths in Scotland alone in 2014. To put that in context, there were 613 drug deaths in total in Scotland in the same year.

The Misuse of Drugs Act 1971 outlaws specific chemical combinations, such as those found in cocaine or ecstasy, but backstreet drug chemists working on NPS constantly devise new chemical combinations which mimic these drugs but are sufficiently tweaked to fall outside what the act proscribes.

The government can, though, place Temporary Class Drug status on any new drug on the recommendation of the Advisory Council on the Misuse of Drugs (ACMD), which then makes it illegal.

The Europe Drug Report 2015 says new psychoactive substances were detected in the EU at a rate of around two per week last year, bringing the total number of substances being monitored by the agency to over 450, with more than half that figure identified in the past three years alone.

Where do they come from?

China’s largest city Shanghai has been reported to be at the centre of NPS manufacturing, with industrial size factories producing tonnes of chemicals destined for the streets of Europe and the west.

Detective Inspector Michael Millar, who led Operation Redwall - Police Scotland’s crackdown on NPS’s last year, believes the Chinese market needs to be addressed.

“There is an underdeveloped legal system in China in this area, which we really need to think about, it is a real problem because huge quantities of drugs are manufactured in factories where conditions are not safe and the products are flooding our markets,” he said.

The Border Agency says its staff stop only a small fraction of the parcels containing NPS coming into the country and cannot know for certain how much ends up in the hands of users.

It is not thought that NPS are widely manufactured in the UK, though there have been cases where cannabinoid powders have been liquidised and sprayed on raspberry leaves and sold for smoking.

How are they distributed once they get to the UK?

Traditional headshops, normally associated with cannabis, across Scotland stock NPS though many have been raided by the police such as Harminasion in Aberdeen which was closed by police this June after a sheriff granted an antisocial-behaviour order. NPS are often sold over the counter as bath salts, fish food, and 'research chemicals'.

However, drugs workers believe that legislation governing headshops makes them more dangerous as staff in headshops are forbidden by law from providing users with adequate information on how to take their products.

Emma Crawshaw, chief executive of the drug charity Crew 2000, which specialises in NPS use, said: “Current legislation precludes head shops from providing information on safer use for people who choose to use as this would prove that NPS products are being sold for human consumption and criminalise vendors.

“As a result, the only restriction is that vendors are unable to provide any information such as dose, effect or duration: packets tend to contain the only the names of the chemicals they contain. It’s unlikely that people will be able to judge risk from this alone.

“Vendors can get around the law by stocking products which state ‘not for human consumption’ or ‘not approved for human consumption’ on the label.”

Online marketplaces, though, are the main outlet for NPS with over 150 sites registered in UK. Users can buy substances by the gram and they are normally far cheaper than illegal drugs such MDMA.

Health implications

Much of the concern over NPS derives from the lack of knowledge surrounding them. There are no reliable figures on the number of people who use them, for instance. The constantly shifting make-up of the drugs also means medics must play a guessing game when treating users who have overdosed.

NHS Greater Glasgow and Clyde’s Dr Richard Stevenson, Consultant in Emergency Medicine said: “NPS are an on-going problem with patients presenting at our emergency departments.

“People are ‘self-medicating’ using various drugs to counter the effects of others leading to poisonings.

“When a drug is banned or made illegal, users are searching for legal alternatives, but due to differing doses and effects people are miscalculating the amount required for the same effect.

“In addition to the physical health risks associated with taking these chemicals we are also now starting to see patients with increased mental illness caused by ‘legal highs’.

“We need to inform young people of the dangers that these products pose as it is often assumed that because the products are freely available and marketed as a ‘legal high’ that they are therefore relatively safe.”

Though the medium and long term effects of NPS are unknown many users report feelings of paranoia and other physiological problems. Anecdotally, young people who the Sunday Herald have spoken to say that they've seen users collapse within minutes of taking legal highs.

What next for the underground NPS market?

The UK Government has proposed a bill which aims to ban all psychoactive substances from sale and distribution, though drugs charities are concerned it will only drive the market underground.

Emma Crawshaw, from Crew 2000, said: “Banning substances is likely to take their direct supply away from our high streets and potentially reduce some ‘impulse’ or curiosity purchases.

"However it is also likely to drive a thriving, adaptable and profit-driven market underground, leading to people buying from even less accountable vendors (dealers) who may well cut products [with other substances] to stretch profits further. This would present additional health risks and complications.

“We have already seen ethylphenidate [a psycho-stimulant] on sale in unmarked bags since the Temporary Class Drug Order was enacted this April banning supply."

Police Scotland have backed the proposed bill saying it will give them the necessary powers to deal with the boom in NPS.

Detective Inspector Michael Millar said: “We would welcome any legislation that makes policing NPS use and distribution more effective. At the moment there is a gap in in the law between the border agency, trading standards and ourselves through which NPS’s can slip, this new legislation would help fill that gap."

What next for users like Rory?

"I managed to graduate," he says, "but I was in a bad way, I got a job with the construction company I had been on placement with but I just couldn’t do it.

"So I smoked this stuff for a year almost every day. It was hard to stop until I started hearing things and seeing things and having psychotic episodes, I would get so paranoid I stopped, but I became very depressed with suicidal thoughts, very strong suicidal urges.

"I was so depressed I quit my job and got on disability. It was hell, I felt brain-dead. It’s been a year since I stopped and I am still in a severe depression, I can’t take care of myself anymore and have lost interest in life completely. I don’t know if I will ever come out of this? It scares me reading the reports that NPS can cause permanent brain damage.

"I've tried searching the web for a similar story like mine but I haven’t found any. Before I started smoking this stuff I was already pre-disposed to depression and I started smoking it to self medicate and ironically it made it so much worse, -way, way worse that I have no life anymore. I don’t know if my life is permanently ruined.

"I went to my GP but they actually couldn’t really help me out that much, they pointed me towards drug centres and things but I don’t feel I’m a drug addict, I need help getting over what these things did to me."