The study investigated the effect of caffeine on the completion of simple tasks as well as place-keeping tasks - tasks that need to be completed in a specific order without skipping or repeating steps.

The study looked at the effect of caffeine after a period of sleep deprivation.

• They found sleep deprivation affected both types of tasks and that caffeine helped people achieve simple tasks.
• But caffeine had little effect on the performance of place-keeping tasks.