First Impressions: Fitbit Alta HR - Carmy - Easy Healthy-ish Recipes
Validation of Fitbit Charge 2 and Fitbit Alta HR Against Polysomnography for Assessing Sleep in Adults With Obstructive Sleep Apnea | Journal of Clinical Sleep Medicine
User manual Fitbit Alta HR (English - 46 pages)
Fitbit Alta HR review: Better sleep analysis and heart-rate monitoring, but it's pricey