Nights in Wisconsin cities have become hotter. The cost is beyond just loss of sleep.

No one ever thought of Wisconsin as being in the tropics, but a new report says our cities are experiencing more uncomfortably hot “tropical nights,” raising the risk of a cascade of consequences from a loss of sleep.

Climate Central, a nonprofit organization that reports on climate science, found that countries around the world are seeing a growing number of nights during which the temperature does not fall below 68 degrees Fahrenheit. That’s above what medical experts say is the optimal range of temperatures for getting a good night’s sleep.

The stakes are high — prolonged sleeplessness can cause brain fog, worsen anxiety and depression, and even increase risk of heart attack and stroke. Experts say this is one more example of the effects of human-caused climate change, and that vulnerable populations will feel them disproportionately.