Heat makes people sleepy because of the mechanisms the body uses to keep itself cool, lack of adjustment to warm temperatures and lack of sleep due to exposure to hot, humid nights, according to Global Bioweather. The human body takes several days to acclimate to the heat, and a person who has not acclimatized to warm weather is likely to feel sluggish. Oxygen levels and blood pressure are also lower.

As of 2015, there are 59 fully fledged national parks in the United States that are distributed among 27 states and two territories (American Samoa and the U.S. Virgin Islands).

The average temperature on Mars is -80 degrees Fahrenheit. A summer day near Mars' equator gets up to 70 degrees Fahrenheit, but dips to -100 degrees Fahrenheit at night. Winter temperatures at the Martian poles drop to 195 degrees Fahrenheit.