It usually takes about 20 minutes. It's hot in dog days, and a lot of sweat will be lost in the process of drying your back, so the time of drying your back needs to be decided according to your physical fitness and endurance. If it's the first time to bask in the back, it won't take too long, usually about 20 minutes. In the future, you can gradually increase the sunbathing time according to your ability, but it is generally not recommended to exceed 1 hour, so as not to cause great losses to your body.