Closer deadlines means more urgency, so can it mean less time-wasting studying or homework doing.
But do take breaks! And don’t rush to the point where cost-return decreases!
The psychological effect is related to Parkinson's law, where you become more motivated to do action or/and avoid the consequences of not doing so, because work shrinks to the duration of "now" and "deadline". However, a "fake" deadline somehow diminishes the effect...