dnd 5e – What degree of autonomy is allowed to a target-victim of the spell Imprisonment / Chains?

Theme / Plot-Premise: a great mage has been bound to the uppermost level of a wizard’s tower. Research suggests use of Imprisonment-Chains works best for this long-term restraint story-idea // condition // plot device.

A restrained creature’s speed becomes 0, and it can’t benefit from any bonus to its speed.
Attack Rolls against the creature have advantage, and the creature’s Attack Rolls have disadvantage. The creature has disadvantage on Dexterity Saving Throws.

That said, given both a Handy Cantrip of The Mages and someone to do the shopping, a wizard’s lifestyle may not suffer that much. It is not clear what a person could do bound in such chains. Apparently casting spells is on the list, but what else?

Question: How much freedom does any target-victim have whilst under Imprisonment / Chains?

Possibilities, Concerns & Examples // Can the target-subject:

  • eat &/or drink? – ‘does not need it’, yes… but can they?

  • soil themselves (‘pee & poop’)? / able to clean up thereafter?

  • need sleep / able to sleep (i.e. gets tired, takes ‘short &/or long rests’)

  • study, research, write, design &/or make-follow plans?

  • do exercises? Possibly making use of those chains?

  • cast concentration-type spells – such as scrying &/or even ritual spells?

  • can they attempt &/or succeed at procreation – either individually or with a partner?

It is just hard to imagine a person comfortably chained up for a few thousand years. I will be thankful for any answer that can clear this situation up a bit.

Possibly Related Questions / answered here maybe? / no idea, so sorry:

  • Do Imprisonment-Chains (‘grappled condition’) remove all dex-based modifiers? Is an armour class modifier is a ‘bonus of speed’? Do hand-cuffed creatures parry worse? Do they throw badly in a game of darts? Would a bad-negative modifier still apply to someone chained up – meaning they sort of ‘dance into’ attacks even whilst so chained?

  • Would an Imprisoned dragon (any version) gain age categories over time? Specifically: dragons do NOT age via ghost scare. Do they age via the accumulation of experience, magic, wisdom and experience? Or is all their aging a biological process? If it were biological, the aging from a ghost should work.

  • These Imprisonment-Chains are firmly rooted in the ground (RAW) – what if the target is 60′ to 120′ up… on a wooden floor? How are they so chained on a ship? Or in the air due to a kite or hot air balloon?

  • Can the caster modify-choose how much spare chain the recipient-target gets? Obviously ‘zero movement speed’ means ‘not going anywhere’. Would / could casters give zone-areas for targets so they are tethered like dogs?

  • Could an arch-mage or any creature with 9th lvl version of dispel be able to remove their own binding – or MUST this be externally outsourced? Could two mages impriso-chained nearish to one another also free one another… but not themselves?

I have many more questions. If any of these ‘fit’ into the question above, please include them. If not, i shall add them to my ‘barrage of future queries’ for my fellow Stackies / Stackers / Boys o’ Stack. My thanks in advance.