Brain activity, and in particular which hemisphere is relatively more effective, is correlated with the dominant nostril (i.e., the nostril through which most of the air is exhaled when breathing through the nose). Since each side of the brain plays a different role in different types of activities, it may be better to conduct certain activities when a certain nostril is dominant. Described herein are systems and methods for suggesting activities according to the dominant nostril. In one embodiment, a system includes a sensor and a computer. The sensor takes measurements of a user that are indicative of the users dominant nostril. The computer predicts, based on the measurements, which of the users nostrils will be the dominant nostril at a future time and may suggest having a suitable activity accordingly.
