I wear a nightly mouthguard currently, but i was wondering if any damage from bruxism is reversible over time (does enamel heal)?

Depends: Damaged enamel can be rebut if the damage is discovered early.

Bruxing enamel away: Enamel worn away from bruxing will not grow back. Enamel does have the ability to remineralize to a degree, which can be enhanced by certain toothpastes and rinses available, but depending on the extent of the wear or breakdown that has taken place, fillings, bonding, veneers or crowning of teeth may be necessary to restore lost enamel. The extent of the wear determines the extent of the treatment.

Unfortunately..no: Ename has no ability to heal/'grow back'. Main purpose of your nightguard is to prevent further damage. Good Luck!

Enamel doesn't grow: Once worn away, enamel is gone forever... it does not grow back. Keep wearing the nightguard to prevent further damage.

Not reversible: Nightguard is to protect your teeth and it may prevent you from needing more dental work in the future.