Determine Whether the Following Is Valid or Invalid

Short Answer

Determine whether the following is valid or invalid:
I finally discovered the mystery of why hard beds are good for you.Here's the story:If you have a hard bed,then you cannot stay comfortable for long periods,and when you can't stay comfortable for long periods you roll around a lot.If you roll around a lot,then your joints don't ache from being in one position too long.Therefore,if your joints ache in the morning from sleeping too long in one position,then you don't have a hard bed.