Can't get a goodnight's sleep because of cruising SM sites.

It sounds like whatever method you're trying to end this habit is ineffective. It looks like all you've been doing is "spending a few days off the site". I don't think that's going to be enough. Abstinence from an addictive behavior isn't enough to eliminate the behavior, as odd as that sounds.

1. You need to figure out why you're relapsing. Look for a pattern. Is there a regular event that triggers it during the week? For example, when I was relapsing really frequently, I was visiting my family once a week. Usually, as I was driving home, I would start to feel urges to watch porn and masturbate. Identifying that as a trigger for my addiction was enormously helpful in preventing relapses in the future. I didn't have to stop seeing my family or anything like that, I just knew that I had to brace myself and prepare myself mentally for the urges that would come afterwards. Try keeping a relapse journal every time you relapse. Write down how you were feeling before the relapse occurred. Write down what you did the day the relapse occurred before you went back to the site. Write down anything you think might be relevant to discovering a pattern in your behavior.
2. Abstain from using the site. Although I said that abstinence isn't going to be enough, it is important to mention it nonetheless. Every time you go back to that site, you're feeding your addiction and making it stronger. This might seem obvious, but it's a prelude to step #3...
3. Replace the site usage with healthier activities. Here are a few I like: cook a nice meal for yourself, exercise, practice a musical instrument, work on a personal project, clean your living space, meditate or pray, write in a journal, post on this forum, call a friend or family member, go for a walk outside. Only when you replace your addictive behavior with healthy behavior will you start to heal.
4. Practice self-love. You keep going back to this site because there is something going on in your life that you're unhappy with. It might be loneliness, it might be insecurity, it might be the way you look, it might be frustration, it might be boredom. Whatever the reason, you need to find out what it is and start the healing process, and you will only find out what it is by looking within. Once you have identified it, recognize that it is not who you are. I can't stress how important this is. You have to recognize that the thoughts you have about yourself or the emotions you experience are not who you are. You are something else entirely.

That's all the advice I can offer for now. I hope this helps you in some way!

 

Don't worry about the late reply. We all have real lives to live, and I'm certainly not going to hold it against you

Yeah, the feeling of loss of free time is a new problem for a new generation. These applications we use on the web (facebook, instagram, twitter, youtube, etc) are designed to use up as much of your time as possible to maximize your exposure to advertisements. It's no wonder you feel free when you're disconnected from the internet.