In the study, 117 volunteers with mild to moderate depression participated in either a web-based self-help CBT program plus an internet discussion group, or an internet discussion group alone.

Overall, 37-percent of patients withdrew from the program because it was "too demanding".

Those who continued reported significant improvements to their psychological well-being.

Dr. Peter Haywood, consultant clinical psychologist at the South London and Maudsley NHS Trust says, "Self-help materials can be extremely helpful. Obviously it will not work for everybody."