It took a long time to fix. Here's some things I tried. Some may have helped or none may have helped.
* I bought blackout blinds and use a sleeping mask (sometimes earplugs)
* I bought a bright light (https://www.amazon.co.uk/gp/product/B07FFJYMVS) and a smart plug. 15 mins before I wanted to wake up I would have a timer turn on the light.
* I eat healthier in all regards
* I started working out
* I started walking a lot more
* I stop drinking coffee at 11am (and drink tea after that)
* I stopped some doing some things late at night (after 23:30) (gaming, programming, eating, using my phone)
* I started listening to audiobooks