Dog won't sleep at night

My 2 year old pug Nala normally loves to sleep whenever. The last 3 nights she won't sleep during the night and is extremely restless, panting and wanting my attention. In the day she seems fine - eating, going to the toilet, wagging her tail ect

Hello!   The most common reason for this, is pain.  It is not unusual for dogs to experience mild to moderate pain at night and not during the day.  During daytime,  life is full of excitement and distrations, but at night, they are alone with their pain.  I wonder about things like pancreatitis, arthritis pain and so on (think how joints get stiff later, not while doing the exercise).

However, there are other reasons;  perhaps she is pregnant or coming into season for example.  More seriously, I wonder about toxic conditions such as closed pyometra.  I also wonder about her heart and breathing.

So, lots of possibilities there ranging from emergencies to mild hormonal fluctuations.   I think that you ought to call your vet and ask whether she can be properly triaged over the phone in case an early appointment is needed.