The relation between daily activities and scrotal temperature.
Plain-language summary
This study set out to find which parts of an ordinary day actually move scrotal temperature. A thermistor (a small temperature sensor) was clipped to the underwear of 101 men and logged scrotal skin temperature every five minutes for 24 hours, while the men recorded what they were doing. Sitting at work was the strongest influence and it stacked up with time: under an hour of seated work ran at a median of 33.1 degrees Celsius (91.6 degrees Fahrenheit) against 34.7 degrees Celsius (94.5 degrees Fahrenheit) at six hours or more, and seated work accounted for 31.5% of the variation in temperature across the whole day. Sitting during spare time made no difference, and neither did the size or the reported tightness of the underwear. A separate modeling experiment estimated the gap between scrotal skin and testicular temperature at no more than 0.1 to 0.6 degrees Celsius (0.2 to 1.1 degrees Fahrenheit), which is the argument for taking the skin reading as a stand-in. This comes from the same Danish research program and the same 24-hour measurement protocol as the study of temperature and semen quality already in this library.
Key findings
- Seated work was the strongest determinant of scrotal temperature, and the effect grew with the hours spent seated.
- Under an hour of seated work ran at a median of 33.1 degrees Celsius (91.6 degrees Fahrenheit), against 34.7 degrees Celsius (94.5 degrees Fahrenheit) at six hours or more.
- Seated work accounted for 31.5% of the variation in temperature across 24 hours.
- Sitting during spare time showed no relationship with scrotal temperature, and neither did the size or reported tightness of the underwear.
- Night readings ran 1.2 degrees Celsius (2.2 degrees Fahrenheit) higher than daytime readings.
- In a separate modeling experiment, the authors estimated that scrotal skin temperature sits within 0.1 to 0.6 degrees Celsius (0.2 to 1.1 degrees Fahrenheit) of testicular temperature.
How to analyze the study yourself
- Study type
- This measured everyone once, over a single day, which is well suited to showing what moves a temperature reading and cannot show what that does to a man over time.
- Population
- One hundred and one men, each logged for a single 24-hour period.
- Funding
- Not reported
- Takeaway
- This study found that seated work was the main thing driving scrotal temperature, accounting for about a third of the variation across a day, while sitting in your own time did nothing and underwear size and tightness did nothing either. If you want the number lower, the hours you spend seated at work are where it moves. It is worth knowing this study measured temperature only and never looked at semen, so it says what raises the heat and not what the heat costs you.