I think this topic has been covered before, but I'm too lazy to dig up the BPL link.
It's normal to have a different sleep pattern when in the woods.
it's not the same as your soft nightly bed mattress.
There is no TV to drain you to sleep.
Your ears are not used to the night sounds of the woods.
Temperature varies greatly (versus your well insulated bedroom)
Altitude, hydration level, lumbar support, salt & sugar intake, caffeine or alcohol consumption, the absence of the comforting snoring of your pets or domestic bed buddy, the anxiety of the trip planning, your mind is concerned that you didn't bring a projectile weapon, you regret and feel guilty arguing on BPL against bringing along such a weapon, you feel like a hypocrite because you convinced others to camp without a projectile weapon but you secretly wish there was an armed security guard outside so you could sleep easy.