Well, what they don't really explain to you are details of a full-time research. I will explain:
To finish excellently well, technically 24 hours a day is not enough!
You need minimum 60 hours a week (these times are for Christians only cos church is subtracted from the hours).
Having a Mon-Fri five hours a day job? I strongly advice not to Dare! I've got almost same dilemma
Living two hours by road travel away from University? Your biggest nightmare!
Put all of these and extra personal work going, you can understand my point. Sleep is now a luxury. Four hours of sleep is a great gift!
If you are considering a research postgrad, mostly a PhD.. Think strongly on these things. I am caught up now. Don't get caught up!