What times do you ride? If you're going to bed too soon after riding it may be that you are still full of adrenaline from the ride. It is unlikely hat you are a night rider though, I don't think many are as a general rule.
All the same try things like hot milk, warm bath before bed. I'm a terrible sleeper but i've started drinking more milk and taking more baths before bed, I was a shower man - not a muckack, and my quality of sleep has got better.