Yes, it is contagious, there is a physiological reason why laughter is contagious. A chuckle triggers areas in the premotor cortical region of your brain involved in moving facial muscles that correspond to the sound. In this way, we laugh, and even laughter sounds involuntarily make us laugh.

That’s why you laugh for no reason when you hear someone laugh in a way.

Laughter improves the function of blood vessels and increases blood flow.
It can help protect you against heart attacks and other cardiovascular problems.

Laughing burns calories. Laughing for 10 to 15 minutes a day burns about 40 calories, causing you to lose 3-5 kilos a year.
Laughter relieves anger.
Laughter helps you live longer. A Norwegian study found that people with a strong sense of humor live longer than those who don’t. It was especially noteworthy for those battling cancer.

You can try some free mobile apps to have a laughter therapy such as Laughter-Therapy