Hi! Your question is a great question!

I think the answer is multi-factorial.
At night, many things change. We change our bodily positions for long periods of time, this may change our circulation some. We change what we do and do not eat, we may even change medications (some taken at night, others during the day). We may be more distracted from pain during the day because we are pre-occupied with other matters and with other senses (sights, sounds, etc.) Weather conditions (barometric pressures, humidity, temps) may change. We may be feeling pain we'd provoked with our daily activities or this may be additional pain due changing factors at the moment.

Lots of variables!
We may each be very unique in our response to any one variable.
Thus, this can become a question pertinent to each individual?

It may be interesting to track some variables which seem to make a difference for you. This may help you to define why you experience more pain at night?

I hope you find 100% relief pronto!

My Best to You,
DejaVu