Just consider that he might just be turned on by your hot body.
The penis is a very strange organ in terms of its job and the way it traps blood inside it. Below are some reasons doctors think guys' bodies wake up ready to bone.
According to a study by the Society for Endocrinology, it could actually be that as certain parts of the brain shut down during sleep, his brain is no longer keeping his penis in check.
In the morning, it's going to be on the highest testosterone level. He'll have all day and also noting that morning boners tend to stop when men reach their 40s and 50s and their testosterone levels dip.
There's no other place in your body that has to trap blood for an extended period of time. The penis is expected to trap blood for a half hour or an hour and be fine afterward. This could be part of the programming that reminds the penis about the way he does its job.
Just because a guy is waking up with a boner, it doesn't necessarily mean he's been dreaming about his crush. The brain is still receptive to physical stimulation when it's asleep, so sleeping close to his partner can absolutely set it off.
Waking up with an erection and the urge to pee is what’s commonly referred to as a “pee boner.” Unfortunately, there’s very little scientific evidence to support this theory. Plenty of guys have probably experienced the symptoms of a pee boner when waking up and probably jumped to this conclusion. But the body has plenty of other systems in place to prevent bedwetting, so this doesn’t seem likely.