Insomnia, as mentioned above, can be a sign of over training but there are a few things you can do to help improve your sleep hygiene.
As mentioned by @abicarver relaxation techniques can really help. You can also try to listen to relaxation music or “white noise” (such as rain etc) before going to bed. If you’re still struggling after a few days of taking it easier on the bike then there are other things you can try.
Make sure your bedroom is noticeably cooler than the rest of the house. Either no phone or TV for 2 hours before bed - blue light from these devices (phones in particular) prevents our brain from making melatonin, our natural sleep chemical) or you can buy blue light filter lenses/glasses to wear 2 hours before bed. Magnesium supplements 30mins before bed can help (will also help from a muscular perspective too!) but preferably in the form of citrate or glycinate rather than oxide or carbonate etc due to absorption rates/ability. Glycine powder before bed (about 10g) can also help with sleep as well as tissue damage repair. Failing even those there are other things you can try like Theanine, 5-HTP and so on. Beyond that, you can buy melatonin but it is technically prescription only in the UK but legal to buy in other countries such as America, and you can buy it online at Biovea if you really want to, but I wouldn’t advise using it unless you really need to.
I’m sure, having said all of that, that a bit of recovery from the bike and you’ll be OK, but if not, there are a few things there to help you out I’m sure.