But very often we don't have enough time fully to have a sleep, and it can negatively affect our organism. 
The sleep debt causes jumps of level of a special hormone which strengthens feeling of hunger and reduces efficiency of hormones peptides suppressing appetite. To compensate a lack of a dream, you start eating more, you want sweet and the refined carbohydrates.

The lack of a dream also raises level of such hormones of a stress as a cortisone which kills cells of a brain in the memory and mood center.

The dream isn't neither inconvenience, nor luxury. It is part of regular work of an organism on personal care and repair. Lack of a dream it that distinguishes an unhealthy way of life which is accompanied by fatigue and inability to concentrate, from life when, having well slept, you feel full of strength and energy and in full contact with the world surrounding you.