Does bedding need ironing
Short answer: No, if you shake it out and hang it properly. Creases in bedding disappear on their own under body heat during the first night.
What works instead
Take the cover out of the machine straight away, shake it out firmly and hang it smooth. Those three movements replace an iron completely.
Why it works
Creases form when fabric is pressed together while wet. Shaken out while still damp, the fibres straighten by themselves as the water evaporates. See bamboo bedding.
If you want to iron anyway
Use low heat and iron while the fabric is slightly damp. Bamboo viscose goes shiny at too high a temperature. See bamboo sheets and bamboo pillowcases.
Frequently asked questions
Does ironing make it look better
Slightly, but the difference disappears after the first night.
What about a pillowcase
That is the one place many people see a difference. Iron it if you like.
Does a tumble dryer help with creases
Yes, if you take the laundry out while it is slightly damp.