Manifest this power up to eight hours before you sleep. Prior to sleep, clutch in your hands the item you would like to store elsewhere. When sleep finally comes (normally or induced), your dreamself finds a secure portion of the Shallows that only it can access, which is referred to as your dream vault. Any item on your person or grasped by you as you fell asleep is with your dreamself (up to 10 lbs. per level). When you wake, the selected object is no longer with you physically—you safely stored it in your dream where no one can access it but you. Objects remain stored until such time as you manifest this power again to retrieve them, and you can bring them back one item at a time (but see this power's augmentation).
You cannot manifest this power while already in a dream environment.
Mind vault doesn't put you to sleep or make you more likely to sleep, but if you manifest it any time prior to sleep, you can access your dream vault. While your dreamself is in the vault, you can access items stored there with previous manifestations of the power, if any.
If you have the Lucid Dreaming† feat, this power can serve you well in another way. Besides acting as a place to store valuables, the dream vault can allow you to catch up on your reading (if you have the tome you wish to read with you in the vault), or, if you have assembled all the requisite physical materials needed (through multiple manifestations of this power), you can accomplish other tasks. For instance, if you brought or stored the proper items, you could repair weaponry or make arrows (though normal skill checks apply). Your lucid dreamself can stay in the dream vault for a maximum of eight hours. Any external force that would normally awaken you also wakes you and ejects you from the dream vault. When your dreamself leaves the dream vault (and you wake up), you may take any one object with you back into the waking world. This object appears in the hands of your physical body as you wake.
The down side of using Lucid Dreaming to catch up on tasks in your dream vault is that you do not gain the restful benefits of sleep, including power point recovery.
No matter where you are located physically when you sleep, you can always access your dream vault. (Note that you can't fall asleep while physically visiting the Shallows or Dream, and a dreamself cannot fall asleep.)
For every additional power point you spend, you can bring one additional object into the dream vault (of up to 10 lbs./level) when you manifest this power. Similarly, you can expend additional power points to remove more than a single item from the dream vault when you wake (1 power point per item, so long as the total expenditure of power points for a visit to the vault, including the manifestation cost of this power, does not exceed your manifester level).