Going to sleep late is not insomnia.
Pascha, you should know that there are two types of insomnia. One type is difficulty in falling asleep. This can be easily treated by ingesting anti-histamines at bedtime (due to the drowsing side-effect) though (DISCLAIMER) I am not advising that you do so unless you consult a doctor.
The other type of insomnia is difficulty staying asleep. This is not treated by sleeping pills, because as you noted, they wear off before the problem kicks in. If you have this type of insomnia you really need individualized treatment.