Hello, it is possible that the cause of your problem is related to the fact that you are lying down, rather than the environment or the time of day. I recommend that you go see a doctor to rule out a physical problem. To help the doctor make a good diagnosis, try the following: 1. At night, sound an alarm to wake you up, but do not lift your head. Stay lying down. Watch for your nose to start running anyway. 2. Take a nap during the day, somewhere other than your bed. When you wake up, watch for a runny nose. This information will be very useful to the doctor. I hope to see you soon.