I wouldn't put them under the bed, it may be warm there but the seed potatoes need light. It's absolutely essential. If they don't get light the sprouts will be white rather than green. And you want healthy green sprouts.
I explain this on this page of GardenAction:
Update on my Potatoes, I planted both varieties Rocket & Foremost on Mothersday ,22nd March, the flowers appeared on the Rocket variety last week,today I had a rootle around the Rocket and I found potatoes bigger than golf balls so really could have dug a bate last weekend,will wait until the Foremost has flowers on before I have a rootle around them.