Flow state is a term coined by psychologist Mihaly Csikszentmihalyi (Flow) to describe a state of deep focus on one task or topic. Csikszentmihalyi argues that people access a flow state when they are doing something that greatly interests them and is challenging enough to require their full concentration, but not so difficult that they give up. Johann Hari argues that enjoying flow states is a key way to regain the ability to focus.

The Rapid Eye Movement sleep cycle is the deepest state of sleep. Having several uninterrupted REM cycles per night is crucial to helping the brain repair itself, integrate new knowledge, and focus the next day. Hari claims that chronic sleep deprivation is harmful to attention in part because it prevents the benefits of multiple REM cycles.

ADHD is diagnosed by doctors or psychologists in adults or children who struggle with attention. Its symptoms include an inability to focus for long stretches of time, with the added component of hyperactive behavior. ADHD diagnoses have increased dramatically in recent decades, and a substantial number of children in the US are now medicated for the disorder. However, the scientific community has not reached consensus on ADHD, with some scientists emphasizing its genetic component and others pointing to evidence suggesting it is largely caused by environmental factors.