Before choosing the first three built-in lifestyle factors, we performed a comprehensive analysis of how lifestyle affects cognitive performance. We came up with a list of potential variables to include. It was long—though perhaps not as long as you'd think (see Appendix, below). Three lifestyle factors came out on top for including in BrainLabs.

We wanted to make sure that journal entries are:

Strongly and consistently linked with cognition in the scientific literature.
Variable over time—they will have days when they are high, and days when they are low.
Trackable by almost everybody, every day, accurately and without special equipment.
Linked with each other for more complex analyses.

Physical activity, sleep, and stress best fit these criteria. Each of them affects cognition, alone and in combination with each other, as they vary over time. Plus, they are easy to track quite accurately every day, even if you do not enter them right away and have to rely on your memory.

We will be expanding the lifestyle tracking capabilities of BrainLabs over time. If you have suggestions for other types of journal entries, we'd love to hear from you.

Appendix: Other Journal Entry Types We Considered

Here are some of the other variables we considered including with our lifestyle tracking functionality.

Arousal
Alcohol
Caffeine
Diet and specific foods/herbs
Meditation
Menstruation and pregnancy
Mood
Music
Nicotine
Social interaction
Video games and brain training

Drugs and supplements, such as:

Marijuana
Medications
Nootropics

Individual differences, such as:

Age
Number of children or pets
Education
Employment type, duration, and work schedule
Health (mental and physical)
Location
Personality
Religion
Sex or gender
Socioeconomic status
Weight