Fitbit has just launched its newest wearable device boasting the slimmest design with a continuous heart rate monitor.

Called Fitbit Alta HR, the newest lineup is an upgrade of the Fitbit Alta that was released last year. The new device is the company's slimmest design yet, as the number and size of its components have been reduced by 25 percent compared to those of the Fitbit Charge 2.

Fitbit Alta HR is expected to help the user track both the activity done throughout the day as well as have better sleep. For tracking exercise and calories burned, the wearable has a continuous heart rate feature that will track the number of steps, as well as other physical activities involving other body movements such as spinning and yoga.

As for aiding in the user's sleep, the same heart rate monitor is not expected to slack off during the wearer's sleeping time. Referred to as Sleep Stages, Fitbit Alta HR's new sleep feature can measure the different stages of sleep such as light, rapid eye movement (REM), deep, and even times when the wearer awakens, in order to provide information on the quality of sleep. On the other hand, the device's Sleep Insights feature gives information on how to improve the user's sleep.

These technologies are developed along with experts from Johns Hopkins University, Stanford University, and the University of Arizona. This innovation, along with the device's slimmer design, makes it more comfortable for the wearer to use Fitbit Alta HR even while sleeping.

To make it even more convenient, Fitbit Alta HR is expected to have longer battery life of up to seven days from a single charge, considering the continuous heart rate monitor day and night. As for its design and look, the new wearable also comes in different bands such as metal, leather, sport, and water-resistant.

Fitbit Alta HR is priced at $150 and will be available by the end of the month.