Yes. Soaking in a spa hot tub for two hours consecutively may offer psychological and muscular relaxation benefits, but it also carries health risks such as dehydration, dry skin, cardiovascular strain, and dizziness.

Yes, bacteria in spa hot tubs can indeed cause illness. These bacteria can enter the body through skin contact, inhalation, or mucous membrane infection, causing various health problems such as rashes, otitis externa, and Legionnaires' disease.

The continuous heating, closed-loop circulation, and suitable water temperature of a spa hot tub create ideal conditions for microbial growth. Even adding disinfectants cannot completely eliminate the risks if the water isn't changed for an extended period.

When you soak in a spa hot tub at 37–40°C, your body undergoes a series of physiological responses: Warmth promotes vasodilation (slightly lowers blood pressure) Warm water has a natural vasodilatory effect, usually causing a slight decrease in blood pressure.

In fact, it's generally not recommended to leave the water in the spa hot tub if it won't be used for an extended period in winter. The reason is clear: when the temperature drops below freezing, pipes can burst, joints can break, filters can rupture, and even the outer shell of the hot tub can crack.

The buoyancy of water reduces pressure on joints and muscles, especially in the shoulders, neck, and lower back. Muscle tension is a common physiological manifestation of anxiety. The buoyancy of a spa hot tub relaxes muscles, reducing body pressure and thus lowering psychological anxiety.