Insomnia, some people claim they have it just because they can't sleep. No, this isn't something that simple. A good sleep is acceptable if you don't feel achy when you wake up. I'm not sure how to explain, but sleep quality is one factor that causes insomnia. Even I am currently making this post for the future when I'm suppose to sleep (it's currently 3 am when I made this)

How our brain works at night

Common symptoms of insomnia include difficulty sleeping, waking up at night and having hard time getting back to sleep, feeling tired after waking up, and waking too early. Check for more info with these guides.
There are levels of insomnia and mainly based on how long it lasts; acute (short term) and chronic (long term) insomnia. Truth be told, it sounds like it's not a big deal to be unable to sleep, 'cause some people just wanna stay up late. You know!? I just WANT some good night sleep! It icks me that I have such hard times sleeping, ans as a result makes me hard to focus on my studies, 'cause if my lecturers are really boring, I can simply sleep after they start 15 minutes of lecture, and when I wake up, 10 slides have passed.

This picture explains my life (from high school till now)

And don't think that it's nice to stay up late. The feeling of unable to sleep, the sound of the ticking clock, the complete silence which is supposed to help but not, is irritating.
Sleeping pills and other depressants are advised under doctors prescription, but of course, I'd rather not get into that stuffs. 'Cause our body will make it a habit to depend on the pills, and that's definitely not a thing I want.

On plus side, insomniacs tend to be more creative during their "suffering" moments. This has yet to be proven, but studies have shown that sleep and creativity are both related. You can read some more of it here.

Not my art, but this is what I do at night

Of course, you'd be like, "Well, at least you're more creative because you're an insomniac" NO! It is fun to be creative at these kind of hours. Our brain requires sleep, and when we don't get enough good sleep, we tend to hallucinate.. like, overreact to most stuffs, and I freaking hate that. I'm not sure if others feel the same way, but I get pissed off easily when I just went through insomnia.
If you know me in real life, you'd probably won't know if I just went through insomnia, but you can tell when my "not-so-close" friends told some stupid lame jokes, I just wanna laugh so hard and say "Nice one!", and if they don't get my sarcasm and continues, I would lower it into irony.

I just can't explain why, but I tend lose my optimism if I don't get enough sleep. Imagine sleep as my charger for my optimistic nature, and when I lack it, I'll just say "Whatever" to anything that doesn't seem to amuse me. May seem usual, but (sometimes) behind my "Whatever"s, what I usually meant was "Just buy me a coffee! I need to get my brain juice flowing, if you can't amuse me.. GTFO".
And I just realized I poured all my negativity on this post. Sorry... :P
Well, this is probably my most truthful post ever. Never put in so much truth in one post. EVER AGAIN
For insomniacs out there... how do you usually feel when insomnia hits you?