Her statement was read out in Northampton Crown Court yesterday (March 14) at the sentencing of four men for a string of eight robberies carried out between September and October last year.
In each incident, which targetted bookmakers and small shops, a man with an axe would leap over the counter and smash the till open, take the cash inside and leave.
The cashier girl, who cannot be identified for legal reasons, said in a statement read out by prosecuting barrister Lisa Hardy: "After the robbery I went home and was in total shock.
"That night I couldn't sleep. My mum came into the bathroom and I jumped thinking it was a robber.
"I kept thinking of the sound of the axe crashing into the till over and over again.
"I've become a more on edge person. My sleeping pattern has been affected and I keep having nightmares. I don't want to go to work some days, and I think everyone entering the shop is a potential robber.
"With support from the shop, I've attended counselling for my traumatic experiences.
"I want them [the robbers] to see that they have changed people's lives just because they wanted to steal money from the shop."
Thousands of pounds were stolen in the spree of robberies that hit four bookmakers and four convenience shops across Raunds, Wellingborough, Kettering and Thrapston.
CCTV shows how a group of men would enter the premises armed with an axe, hammer, knife and incapacitating spray before threatening staff and members of the public.
Text messages exchanged by two of the defendants, Lee Frederick Cole and a youth who cannot be named for legal reasons, were read out in court. They show how the robberies were planned in advance, and discuss if balaclavas, weapons and getaway drivers had been arranged.
One read: "Want to hit that bookies later?"
Another read: "No such thing as being greedy. Easy peasy."
In sentencing one of the youths, Judge Rupert Mayo said: "These offences were planned in advance and your text messages to read are a very frightening experience. I hope in time you will find them chilling yourself. For now, I imagine you find them amusing."
Lee Frederick Cole, aged 26, of Allen Road, Rushden, who snickered, grinned and yawned as his offences were read out, was sentenced to six years and eight months.
Brett Stuart Trevor, aged 25, of Church Mews, Judith Road, Kettering, pleaded guilty to a single count of joint robbery committed on 8 October 2016. He was sentenced to 44 months.
Two others, who cannot be named for legal reasons, also pleaded guilty to the conspiracy. A 17-year-old boy was sentenced to 50 months in youth custody and a 16-year-old boy pleaded guilty to a single count of joint robbery committed on 8 October. He was sentenced to 38 months.
The 16-year-old also pleaded guilty to a separate offence of armed robbery where a handgun was used to scare staff and steal money at Ladbrokes in High Street, Kettering on January 10, 2017.