@Kinetix I'd say it comes and goes depending on how obsessed I am with something before I'm supposed to go to bed. My tentative bed time is 10 PM, but it's more often 11 PM and I have had obsessive bouts until 2 AM, once until 5 AM (that one hurt).
I also only nap when I'm completely exhausted, which happens regularly when I miss my expected bed time.