Zinc is useful for those who are exhausted. But this is nervous exhaustion caused perhaps by over work or study which results in a headache or exhaustion or eye problems.
Interestingly persons needing this remedy will be restless along with their exhaustion. They may be fidgety, especially in their legs.
Compare this remedy with Cocculus and Coffea for the exhaustion.
Fidgeting, twitchiness, especially in legs
Eye problems
Headache
Tiredness