Ask HN: Sleep supplements that worked for you (excluding melatonin)

I'm in the UK, and unfortunately melatonin is not available as an over-the-counter product. Only a doctor can prescribe it in the UK. Purchasing it online is not easy. For example, it is not possible to purchase via Amazon.de or Amazon.com for delivery to the UK due to regulations (same for eBay.co.uk).

What non-prescription sleep supplements have you tried? Which ones worked for you that you recommend?

For example, CBD (cannabidiol) oil is widely available without prescription and is purported to aid sleep. If you have tried it, have you found it helpful?

Any other non-prescription supplements you have tried (with success)? Thank you.