Cyberstalking behaviour can be linked to people suffering an online addiction, who increasingly lose touch with the real world because they are tapped into social networks and websites, experts warned.
People spending a lot of time on their computers or smartphones can find their ability to form normal healthy relationships away from the screen "shrivels", according to Dr Emma Short, director of the National Centre for Cyberstalking Research (NCCR).
This can lead to them becoming fixated on people with whom they have a solely virtual relationship and engaging in stalking behaviour like bombarding a person with messages or other attention over a sustained period of time.
The NCCR, based at the University of Bedfordshire, has produced a new ebook, A Practical Guide To Coping With Cyberstalking, released to coincide with National Stalking Awareness Week, which starts today.
Psychologist Dr Short, one of the co-authors of the book, said: "It (stalking) can be a consequence of internet addiction, so your cyberstalker's ability to form normal healthy relationships is compromised.
"If you are spending all your time online, your relationships largely become online. That bit of your life starts breaking down and you become more invested in online relationships and more likely to become fixated on those."
The book seeks to provide help and advice for potential and past victims, saying that many suffer lasting psychological harm.
It claims more than a third (35%) suffer post-traumatic stress disorder (PTSD), a problem more associated with soldiers returning from war zones.
Writers who contributed include psychologists, computer science experts and police officers. It includes a chapter written by Dr Short and Professor Jim Barnes on "problem internet behaviours" that can lead to online stalker activities.
It talks about how relationships, work and daily life can be adversely affected by "compulsive internet usage" that means they don't strike the right balance between being online and the other parts of their lives.
Dr Short added that many people often go online to escape real-world problems, like anxiety, depression and stress. She said: "You have this lack of social support and again, we know with stalkers generally the more wounded they become in terms of loss of social connection, social support, job - because if you keep breaching injunctions you lose your job, you lose everything - and the more you lose the more dangerous you become.
"It is the same with social support, the more your offline social world shrivels the more likely you are to become fixated with online relationships."
In half of online-only stalking cases the perpetrator is a stranger or their identity is never known, Dr Short said, far higher than in cases where there is real-world stalking as well, which is more often carried out by people known to the victims. This makes it hard for victims to assess how much of a threat a cyberstalker may be.
The book also addresses the difficulties victims face, with many thinking they will not be taken seriously or are too embarrassed because of material sent to them or posted online about them.
Last week new laws targeting so-called "revenge porn" came into force, with those who share sexually explicit images without consent facing a jail term of up to two years.
Prosecutors previously had to find evidence of harassment or copyright infringement when seeking to take someone to court.
Dr Short added: "Where there is sadism, where people actually are trawling sites to look at people who are frightened or hurt, or have been involved in non-consensual pornography, which is really what revenge porn is, it is likely those sites will attract people who are potentially more dangerous but who may only be enacting one aspect of their personality. Those are the places where a greater understanding of how to assess risk is necessary."