Electric breast pump

I have just started pumping but I am also breastfeeding. Do I have to wash and sterilise the breast pump after each use or just once a day? Obviously I use it at different times throughout the day and I am sterilising after each use but it’s very time consuming. Also, if you have any tips for pumping, I’d appreciate it. My son wasn’t getting enough at night time so he was refusing to sleep in his own bed, but now I pump 5oz in the morning and he has that before bed and he’s staying in his own bed now. So all this time it turns out he was hungry at bedtime.