Other benefits of melatonin include general neuroprotective effects, as melatonin is a powerful antioxidant. Melatonin also has several anti-cancer properties, and is currently being investigated for its role in fighting breast cancer.
The date of substantial completion is extremely important, because it determines the date that a contractor is no longer fully liable for delayed completion or for minor incomplete details. After substantial completion, the owner again becomes responsible for the property, i.e., security, utilities, etc.
In my experience, I usually hear substantial to describe a part of something that is either a very significant part or a part that could stand for the whole (i.e. it vaguely indicates the figurative or literal size of something).