As a student, sometimes I run on insufficient sleep while drawing on magick energies to stay awake and focused.
Energise the Base Chakra for general fatigue and tiredness.
Energise the Ajna (middle of the eyebrows, below the forehead Chakra) for concentration and willpower.
Energise the forehead chakra for better memory retention and overall health of your nervous system.
Of course your ability to draw/raise and channel energies is better with consistent meditation, physical exercise... and a good night's sleep. (no catch 22 intended)