According to the case's facts, between 2008 and 2013 Narayan indecently assaulted the girls by standing behind them and rubbing their bodies, getting them to climb into bed with him while he was naked while making a game of it.
Narayan also sexually violated one of the girls by rubbing her crotch while in the car and digitally penetrated her.
Because of what he did, the court heard how one of the girls said she now suffers nightmares, can sometimes only sleep three hours at a time causing her to miss school which made her fear her grades would suffer.
She also suffered depression and needed medication, had no close friends because she was insecure, had suicidal thoughts and the trauma of the matter going through the courts made her suffer further.
The other girl said what Narayan did changed her as a person, caused her to have unhealthy eating habits and she swung between anorexia and weight gain.
She described having a lack of motivation, increased anxiety and difficulties communicating with males.
Narayan was a computer sciences lecturer for 16 years, before resigning late last year after he was convicted.
Crown prosecutor Scott McColgan said Narayan's offending was opportunistic and illustrated a "predatory and prurient ongoing interest in these girls".
"Mr Narayan would seize upon moments when he could offend against these girls and do so."
This showed there was some sense of planning or premeditation involved in the offending which was an aggravating factor, McColgan submitted.
However, Narayan's lawyer, Sam Wimsett, said outside of this offending the former lecturer provided service to his community.
He did this through his role at Unitec where he worked for 16 years and as a volunteer at a Hindi school on Sundays.
Narayan's only other convictions were ones for "foolishly" sitting an exam for a student and a "minor incident" involving domestic violence, Wimsett said.
The defendant also has a baby on the way with his partner of two years and so the impact of his imprisonment would be significant on her, the lawyer argued.
Judge Josephine Bouchier said even though he had read the victim impact statement from the girls and was found guilty by a jury, Narayan maintained his innocence.
Adhering to the principles of denunciation and deterrence, Judge Bouchier set a starting point of four years for the lead charge of sexual violation and added a year for the other offending.
She then gave a "modest" reduction for the former lecturer's efforts in the community ending with a sentence of four years, nine months in prison.
The Herald has approached Unitec for comment.
