Open Question: How can I bring up the idea of separate beds with my partner?

We are troubled by sleep disorders (partners: Sleep apnea me: sleepwalking, insomnia), but my partner is very old, and that a couple should always share a bed. Finally, I spend on the computer late at night, a partner wakes up early, turn on the TV. Tension because of this gap is getting worse, and our sleep patterns, but I have been sleepwalking, the result is worrisome. How do you tell people that you love them suffered heavy losses, but can not tolerate sharing a bed?