Actually I dont think its fine - as it's a kind of cheat - it's 1am however it's part of your routine - Nitnem should be done after you have slept and then challenged yourself to be up within 6 hours of sleep - it would equate properly and would be right. Further vichaar is needed here. I also work strange hours and sometimes nights - and a friend of mine asked the question to the Panj who advised if you work nights then come home do sohela goto sleep and get up and do amrit vela. But that is working nights, on evenings work I am home and sleep around 1230 try to be up by 430 - 4 hour sleep - then sleep later after nitnem works perfectly.
However I see via it semes valid as the tranagaa of naam abyaissee Gurmukhs are alive and kicking at 1am onwards and there is not match for that feeling. Only way is to pray for mahraaj to give you the kind of work which will allow normal amritvela.
ਸਤਿਗੁਰਬਚਨਕਮਾਵਣੇਸਚਾਏਹੁਵੀਚਾਰੁ॥