I'm disappointed to see so much effort put into making learning effortless (learning styles, cognitive enhancing drugs etc.). The most basic and critical components of learning is the laying down of memory traces. Making meaningful connections to the knowledge you already have. The act of taking information and going through the process of moving it from information to knowledge and then understanding.
Another critical component of learning involves the correct reactivation of those memory traces. If you can't recall what you've learned, then you haven't really learned it. Laying down memory traces, and strengthening them so they can be reactivated takes energy. Whenever the brain uses energy in a directive fashion effort is involved.
In fact, research into cognition clearly demonstrates that the more effort that is put into learning something, the better it will be recalled in the future. For effective learning, that effort must be in both the encoding (the learning) or the retrieval (the recall). Transferring information from sensory memory to short-term memory, to episodic memory and finally into a stable long-term memory trace is the kind of learning we are trying (or supposed to be trying) to accomplish in higher education. Bjork's (one of the world's leading memory researchers) Desirable Difficulties chapter provides great background reading about the work of memory in learning (that is if you are looking for real research int how people learn rather than the latest fad). The idea that we make it as easy as possible for students to learn is missing the point. Requiring them to invest energy in the process and put real effort into the process is what fosters learning.
Although this might not fit well in a world where the massification of higher education means packing them ever higher and deeper into a lecture hall for the shallow sit down, shut up, face the front while I tell you how to think type of activity that accounts for most of the teaching that takes place in higher education today.