Hot tubs and saunas can serve similar purposes for people, but in completely different ways. A sauna is a room where infrared heat or steam is emitted to produce a feeling of relaxation, increase blood flow, loosen muscles, and sweat for weight loss. Hot tubs allow people to be immersed completely in warm or hot water to loosen joints, relax muscles, improve mood, and increase blood flow. Many people opt for hot tubs over saunas because they are more versatile and tend to work easier in the existing spaces people have outside their home.