Abstract: Tightness of a wearable device can be evaluated through direct observations of how the device responds to a physical stimulus. For example, by applying a varying pattern of vibrations such as a CHIRP signal with a haptic output element or the like to a device strapped to a wrist or other body part, the mechanical and/or optical response of the device can be measured to infer the amount of tension that is retaining the device against the body, or more generally, to evaluate whether the device is properly fitted to a user. Results can then be presented to a user objectively using Newtons or some other metric, or subjectively by providing qualitative assessments of fit. Recommendations for adjustments may also or instead be provided to the user for optimal performance of the wearable device.

Abstract: A wearable optical device is described for optically detecting parameters of interest within muscle, including oxygenation level and/or hemoglobin concentrations. Detected parameters may be used to assess physical performance, such as the extent to which muscle is utilizing aerobic or anaerobic processes. The wearable optical device may include a pressure sensitive strap. Pressure provided by the strap may affect properties of tissue or sensor measurement, for example, by occluding blood flow or mechanically distorting measured tissue. Pressure sensors may be included in the strap, and may be used, for example, to: examine the heterogeneity of a pressure distribution of the strap, allowing a user to manage pressure consistency throughout measurements using the optical device; determine if pressure affects measurements taken by the optical device; and/or manage levels of blood flow restriction, allowing a user to perform exercises with lower levels of oxygen delivery, such as hypoxic training.

Abstract: A wearable physiological monitoring device is configured to determine a wearer's sleep intention. In particular, the device evaluates activity that might be objectively associated with awaking from sleep in order to distinguish between a wearer's intention to end sleep and transitory stirring or other intermittent activity occurring in the context of a longer sleep interval. By evaluating sleep intention more accurately in this manner, the device can advantageously request sleep analysis from a remote server in those instances where a user intends to end a period of sleep (so that this data can be available to the user more quickly), while avoiding unnecessary or redundant server-side processing of sleep data in those instances where a user intends to continue sleeping.

Abstract: A wireless recharging battery can be removably and replaceably coupled to a physiological monitoring device in a manner that securely retains the wireless recharging battery in a precise location relative to a corresponding wireless power interface of the monitoring device, while facilitating intuitive and easy removal and replacement of the wireless recharging battery by a user.

Abstract: An enclosure for an electronic device, such as a wearable physiological monitor, may be formed of at least two different materials, e.g., a first part formed of a first material (e.g., a metal) and a second part formed of a second material (e.g., a plastic). The second part may include an opening to receive at least a portion of the first part therein, where the first part includes an anchor projecting from a surface thereof into the opening of the second part. To ensure that the enclosure is waterproof, a third part that can be chemically bonded to the second part may secure the first part by filling a volume between the anchor of the first part and an adjacent surface of the second part around the opening. In some aspects, the chemical bond between the second part and the third part creates an environmental seal around the opening.

Abstract: Sleep need for a user is assessed using continuous physiological data from a wearable monitor. In particular, by calculating a first sleep debt metric based on user strain and a second sleep debt metric based on accumulated sleep debt, an objective metric can be obtained that estimates an amount of sleep needed by the user in a next sleep period. This approach takes advantage of multiple modes of information embedded in the physiological data, such as a sleep and exercise patterns for a user over one or more preceding days.

Abstract: A strap for a wearable physiological monitor can be adjusted to a desired tension. The strap may include a buckle that retains a length of the strap as the strap is removed from and replaced to the wearable physiological monitor. In this manner, one or more straps may be removed and replaced without requiring readjustment of strap length for a particular user.

Abstract: A physiological monitor switches between a time domain analysis and a frequency domain analysis for determining a heart rate based on objective indicia of signal quality in an acquired heart rate signal.

Abstract: Physiological parameters such as respiratory rate and/or heart rate variability can be measured over time for a user and correlated to physiological and/or hormonal cycles such as the menstrual cycle. By determining the phase of such a cycle in this manner, an automatic coach for the user can recommend phase-specific adjustments to activities such as sleep and exercise.

Abstract: A model of data quality is derived for physiological monitoring with a wearable device by comparing data from the wearable device to concurrent data acquisition from a ground truth device such as a chest strap or electrocardiography (EKG) heart rate monitor. With this comparative data, a machine learning model or the like may be derived to prospectively evaluate data quality based on the data acquisition context, as determined, for example, by other sensor data and signals from the wearable device.

Abstract: A wearable physiological monitoring device is configured to determine a wearer's sleep intention. In particular, the device evaluates activity that might be objectively associated with awaking from sleep in order to distinguish between a wearer's intention to end sleep and transitory stirring or other intermittent activity occurring in the context of a longer sleep interval. By evaluating sleep intention more accurately in this manner, the device can advantageously request sleep analysis from a remote server in those instances where a user intends to end a period of sleep (so that this data can be available to the user more quickly), while avoiding unnecessary or redundant server-side processing of sleep data in those instances where a user intends to continue sleeping.