For babies over 2 months of age, 3 days is the minimum to submit for analysis. However, 7 days is better since sleep can fluctuate from day to day.
At least 7 days is especially recommended when you are trying to tackle a sleep issue that does not happen every night (e.g., long awake periods in the middle of the night, early rising), sleep varies a lot from day to day, or weekends are different from weekdays.
If you have tracked more sleep, include many days when submitting.
So why do we allow submitting just 3 days, if 7 provides a more accurate picture? Because moms and dads are already exhausted! We would rather you get the help you need based off of fewer days of sleep, than nothing at all.