If you take viagra (sildenafil) prior to sleep would nocturnal erections induce priapism?

Possibly: Viagra (sildenafil) and any agent used treat erectile dysfunction can induce priapism. If viagra (sildenafil) is taken at night, then it is possible that a normal erection could last longer and cause priapism. Who actually develops priapism depends on their risk factors such as age, comorbidities including diabetes and hypertension, and use of other medications. The more comorbidities a man has, the less likely.

Unlikely: Don't take viagra (sildenafil) if your 23you don't need it.