Use SMART targets
SMART stands for Specific, Measurable, Attainable, Realistic and Timely. So instead of planning to 'do research' or 'write some of the essay' during a 1 hour slot you should be more specific i.e. 'read and make notes on two articles' or 'write a paragraph on point B (200-300 words)'. That way you know what you need to do and you will know that you have achieved it. This is better for keeping motivated too.