I have the same issue with you. It comes and goes. I've also tried pharmacy supplements some days i get a good sleep but it doesn't quite solve the problem also in the end. Sleeping pills has alot of side effects and could be fatal if OD that's why it's not easy to get your hands on those pills here and I wouldn't recommend you relying on drugs anyways.

Plenty of people say lifestyle change can help and I agree so I'll share what sort of changes I made. You need to find what works best for you though. I've always been living an active lifestyle and i eat mostly nutrient dense food and so far don't have any medical conditions. So technically I will say I'm a healthy individual. If you have any health issues or unhealthy lifestyle to start with you may first start evaluating that and see if it helps with your sleep. I've known people who ate rubbish everyday having trouble sleeping until they ate better quality foods because it helps their body digest better and thus ensuring a comfortable night's sleep.

You can try to list out your daily activities during your sleepless nights and monitor your mood. I think keeping a journal log on this is really helpful to find out what could be the trigger. It could be an underlying stress that's causing it but u may not even realize you're stressed. That was my case for sure. I was super stressed till I had other sleeping disorders like exploding head syndrome etc but I didn't really know I was under that sort of stress coz I seem to handle it quite well on the external side of things. Eventho I'm not caffeine sensitive, I just stay away from caffeine past my morning coffee. If you can go without coffee or tea in the morning then do it, personally I just love coffee way too much. I also workout earlier in the day and make sure after 7pm I'm just fully rested not doing too much and also trying my best to cut off my work by 8pm. Sometimes I take the time to do some breathing and stretches or self-massage to make sure I'm fully at a rested state with no tensed muscles or anything. I also reduce my water intake past 8pm so I don't interrupt my sleep by going to the bathroom which is one my problems also, I'll wake up multiple times at night for this. Then I also make sure the temperature and sleeping condition is just right for me, if it's too bright, close the blackout curtains, too hot, turn on AC like that. Basically I just make sure I don't create any possibilities that could interrupt my sleep. It also helps to put my phone on silent, no vibration also coz I'm a light sleeper. I know this sounds like very OCD but you can try to change your lifestyle slightly to make changes with your sleeping. Doing all this did not cure my sleeping disorders but it made it alot of better, I seem to have more good sleeps than bad these days. And lastly, you should create a scheduled sleeping time for yourself and be strict to stick to it everyday. That means, even on weekends u have to give up those late nights atleast for a few months or until your body is able to adapt to the sleeping time you've set for yourself. At first I set it latest by 1am. Then slowly reduce to 12am. Then now I manage to get myself ready to sleep at 11pm. I'm usually in bed 1-2 hours earlier to wind down first. I'm still trying to put away my phone before bed and do something like reading or listening to audiobooks instead but depends on my mood. I find that when I'm not staring at the screen 1-2 hours before I fall asleep much faster.

I really dunno if this is helpful but I've been going through this for like years and years i wanna say on and off for 15 years already. Been to the doctors and tried supplements but so far the results were not really helping on a permanent basis. I made all the changes like above sometime around the end of 2016 and so far I've only had like less than 2 weeks worth of sleeping issues for 2017 which is really good for me.