When it's storming outside and there's lightning and thunder it can be hard to sleep for me as well.
What I do to help me sleep during a thunderstorm is to close the blinds and pull my curtains shut to help block out the flashes of lightning coming into the room.
I then also wear a sleep mask on my eyes which help me sleep because it creates total darkness which is what I need to sleep.
I also put some earbuds in my ear and listen to some soothing music which helps me drift off to sleep.
In some cases I may need to even take some sleeping medicine which helps me sleep.
Some people cannot get to sleep at all during a thunderstorm and some people sleep better during a thunderstorm.
But about all you can do is to block out the noise and lightning and maybe take some sleeping pills to help you get to sleep.
Or put on some music on your radio or computer and allow the background noise to help you get to sleep.