1. Body temperature is lowest before waking up in the morning, and highest in the late afternoon. A temperature of 99 degrees Fahrenheit might indicate fever at 7 a.m., but by 5 p.m. would be normal.
2. Heart attacks are twice as likely in the early morning as at other times.
3. Births peak in the morning and early afternoon.
4. So do suicides.
5. Body clocks are why doctors often prescribe taking medicines at certain times of day. For example, both aspirin and antihistamines work best taken in the morning. But some types of chemotherapy for cancer may be more effective and less toxic if administered at night.
6. People are much more likely to have sex at night just before they go to sleep than at any other time of the day.