"Scariness" is a very subjective concept, so something that could be terrifying for one person might be a joke to someone else. Because books can't exactly rely on cheap tricks like jump scares or thundering sound effects, there is no way that they can scare you as much as a movie. With that said, if you have a good imagination then the stuff your mind can conjure up is way worse than any movie could ever match. A good example of this would be a book called House of Leaves by Mark Z. Danielewski. Everything about this book makes it unsettling to read as even the style and layout of the pages are done in an unconventional manner. It is one of the first books that I have ever read where the author was able to make me feel claustrophobic. What is even more amazing is that the author classifies the book as a love story.

I'm not so sure about scary, but one book that definitely freaked me out while reading it is Penpal by Dathan Auerbach. The book actually started out as a bunch of creep stories that the author posted on reddit and these got such a positive response that he turned it into a book. Penpal is about a young boy who takes part in a penpal experiment at school where they have to send off a letter that is tied to a balloon. Long after this experiment, the boy receives some disturbing photos in the mail, which is the start of some really bizarre and terrifying events.

Although I am sure that there are plenty of disturbing books from people like Stephen King, Lovecraft, Clive Barker, Poe and the rest of the horror clique, the books that make me double check my locks at night are not of the fictional variety. Instead, its the non-fiction accounts of serial killers and other menaces to society. I have got plenty of recommendations in this regard, so sit back, brace yourself and experience any of these for some real chills.

* Murder In The Family (Burl Barer)
Sometimes the biggest monsters are the ones closest to us. This is the gut wrenching account of how a mother along with her two children were brutally killed by a family member. The part of the book dealing with the trail may be a little dry for some people, but for me it provided a disturbing glimpse into the mind of a person capable of doing something this shocking.

* The Stranger Beside Me (Ann Rule)
Ted Bundy was responsible for everything from burglary and kidnapping to rape, murder and necrophilia, which makes him as close to a real-life monster as you can get. What gets me the most is that his victims, who were mostly young women, thought him to be a charismatic and good looking person. This book was written by someone who knew him personally and considered him to be a friend and it chilled me to the bone.

* Case Files of the East Area Rapist (Kat Winters & Keith Komos)
Words cannot even begin to describe the reign of terror that the man known as the East Area Rapist, Golden State Killer and Original Night Stalker left in his wake. He not only committed hundreds of burglaries, but also raped fifty women and commit dozens of murders. The most terrifying thing about this book is that this monster was never caught, despite all the atrocities that he committed and the clues he left behind.

* Jeffrey Dahmer: A Terrifying True Story of Rape, Murder & Cannibalism (Jack Rosewood)
What scares me the most about Jeffrey Dahmer is that he was found to be legally sane when he stood trial. This is a man who wasn't just a serial killer, but also raped his victims before dismembering them and performing necrophilia or cannibalism. His targets were all men and boys and like many other serial killers he was able to catch his victims off guard with his charm and intelligence.

These are just the tip of the iceberg, there are plenty of other nightmare inducing serial killers that stalked this earth including the Zodiac Killer, the Hitchhikers' Killer, the BTK Murderer and John Wayne Gacy.

Maybe I'm not reading the right kind of books, but I have never encountered anything that left me feeling scared in any way. BUT, there have been a few books that either left me feeling very unsettled or very uncomfortable, making it hard to sleep afterwards. The books that I can remember off the top of my head are Fahrenheit 451 by Ray Bradbury, George Orwell's book, 1984.

This would depend on how old you are. Some of the most horrifying and scary books I've ever read were when I was a child and got my hands on the original versions of popular fairy tales. Just go and read the original fairy tales from the Brothers Grimm and you'll see what I mean.

Just do yourself a favor and ready anything by Edgar Allan Poe or Howard Phillips Lovecraft. Some people consider books like those by Stephen King to be scary, but none of the modern authors have ever come close to the true masters of horror like Poe and Lovecraft.

When I read any horror book I become nervous ownself. How can I read any any horror book confidently?

Since you did not specify whether you mean fiction or non-fiction I would have to go with a book called The Hot Zone by an author by the name of Richard Preston. It is a non-fiction thriller that was published in 1995 already, but I didn't read it until 2014 when it seemed like the only news on television was about a possible Ebola outbreak in America. From what I can remember, there was a man in Dallas who came back from Africa and died from Ebola. The two nurses who cared for him both got the virus as well and I was severely freaked out when I discovered that one of them was in my hometown of Akron Ohio before she knew that she was infected. There was a lot of panic during this time and I remember how terrified I was when there was all the talk of how the Ebola might go airborne and spread like wildfire. I was still in school when all of this was happening and even the thought of going going there or to public places like the mall scared me. It was so bad that my heart literally started beating faster whenever I heard the sounds of sirens outside. I started reading The Hot Zone to find out more about viruses and how they affected the public during outbreaks, but there were a few times where I had to stop reading just to calm my nerves with some music or painting. The way in which the author describes how diseases progress and the effect they have on their unfortunate victims literally made my stomach churn a few times. I now know of course that the author may have exaggerated some of the things like the way in which the virus literally dissolves your organs, but back then with all the news of a near certain outbreak in America it was scary as hell. After a while it became apparent that nobody in our town was getting sick and none of the fearmongering predictions came true, so life slowly returned to normal, but I still get a shiver down my spine whenever I think back to reading that book while huddled up in bed and wondering what I will do if the people around me suddenly developed symptoms.

In spite of the many, many horror books on the market, the actual amount of them that can genuinely be classified as scary are few and far between. One of the only ones that has ever really given me chills while reading it at night is The Exorcist by William Peter Blatty. Even if you have already seen the film adaptation, this book is a real page-turner. Reading it at night is extra terrifying as it is apparently based on a true story, which is not the kind of thing you really want weighing on your mind at bedtime.

It's always funny to me how people say Poe or Lovecraft are not scary, but they read the books in broad daylight with their televisions blaring in the background as they browse their social media feeds between pages. I can only imagine how terrifying these books were back in the days when they were written if people read them at night. Give these books a spin when you are alone at home late at night with only a candle to light your surroundings and they will take on a whole new meaning. I know that the archaic words can make it a little tough if you are not used to them, but after a few chapters it all falls into place and you can experience the stories in all their terrifying glory.

As for Stephen King, I've got nothing against him, but I feel like his output has been very inconsistent over the years and half of his novels that people describe as terrifying barely feels like horror in my opinion. Don't get me wrong, he's got a couple of really good books and even a few horror classics, but nothing that he has written has ever kept me up at night.