Surprised nobody has mentioned this one; it's -very- effective for me and with the most of minimal side effects:
Trazadone 50mg
I will take one right at bedtime and I am I am out within ten minutes. What I really like about it though is the lack of grogginess /haze when I get up. Even after only four or five hours of sleep. But you need to make an effort to get up and get going. If you malinger around the bedsheets too long you will likely fall back asleep. Another plus for me are VIVID-ASS dreams. 90% of the time they are awesome and I'm back with my family having a good time. The depth , vivacity, and extreme detail from the dreams is very uncanny. Never have developed nitemares or anything overtly negative, but the realistic, cinematic detail in the dreams can be intense upon waking up & recalling the experience.
I only need to take one sporadically 2-3 a month at most. There is no urge to redose or dependency issues with it that I can perceive. It's very much nearly a perfect drug for insomnia in my case, and perplexed why it's not more well known for this (it is off-label use for insomnia , whereas it's "official" use is as an anti-depressant.)