Why do people feel sleepy when doing something that is cognitively intense, like studying, reading, listening to a podcast that goes deep into a topic, or playing mind-stimulating games? Why do we feel sleepy when we’re learning?

As we’re learning, we’re taking in a lot of information to compute. In this process, the short-term memory of the brain gets overloaded and the brain tries to encode the heavy influx of data. This causes sleep signals to be triggered

Sleep activation during intensive learning

The more you actively learn (not redo something you already know well), the more sleep signals get triggered and chemicals such as the Brain Derived Neurotrophic Factor (BDNF) are released. The Reticular Activating System (RAS) is also engaged and you start to slip into sleep states

The Hippocampus is the part of the midbrain that is responsible for encoding short-term memory to long-term memory. It is also known that sleep allows the brain to consolidate and deeply process everything we have learned. When we are engaged in cognitively intense activities, the hippocampus feels overloaded and sleep signals are triggered. Why is that? I think that’s the brain’s way of telling “I need sleep in order to digest all the information!”