Ambient light determination using physiological metric sensor data

A biometric monitoring device comprising:

• an electronic display associated with a first side of the biometric monitoring device, the electronic display having a configurable brightness level setting;
• a physiological metric sensor system including a light source and a light detector associated with a second side of the biometric monitoring device, the physiological metric sensor system being configured to generate a physiological metric signal at least in part by:
• directing light from the light source into a user during a first period of time;
• detecting a first amount of light detected by the light detector during the first period of time, the first amount of light including reflected light from the light source and first ambient light;
• detecting a second amount of light detected by the light detector during a second period of time, the second amount of light including second ambient light;
• and
• cancelling at least a part of the first ambient light in the first amount of light based on the second amount of light;
• and
• control circuitry configured to adjust the configurable brightness level setting of the electronic display based at least in part on the second amount of light.

A method of managing power in a wearable computing device, the method comprising:

• directing light from a light source into tissue of a user during a first time period;
• generating a first light detector signal using a skin-facing light detector, the first light detector signal indicating a first amount of light detected by the light detector during the first period;
• deactivating the light source during a second period;
• generating a second light detector signal using the skin-facing light detector, the second light detector signal indicating a second amount of light detected by the light detector during the second period;
• generating a physiological metric signal based at least in part on the first light detector signal and the second light detector signal;
• and
• modifying a brightness level of an electronic display based at least in part on the second light detector signal.