Why does JP drainage increase at night while sleeping, yet I have no drainage during the day?

It is most likely that the fluid is accumulating with the dependent area of the abdomen when you are sleeping. When you are elevated, the serous fluid uses gravity to drain through the Jackson Pratts drains that are on suction. Should the amounts accumulate or the drains stop flowing, it is imperative to seek your Board Certified Plastic surgeon for evaluation. 

Thank you for your question.  The drain that is still producing fluid at night was likely placed in a non-dependent area of your surgical site.  When you are walking around it likely is sitting above the fluid that needs to drain.  When you lie flat the fluid spreads out, coming in contact with the inflammatory fluid and removes it.  I remove drains when there is