Research shows that most sexual activity between couples occurs at bedtime. This article explores some of the biological reasons that may occur. The author suggests that although it is unnecessary for sexual activity to take place at this time, this pattern holds true for most couples.
One of the reasons this occurs is because it is convenient. When people are in bed together, they are available to each other, so it is a logical time to have sex. Another reason nighttime is a popular time to have sex is that it may encourage fertilization since gravity could cause sperm to fall out, and if the couple goes to bed after sex, this would allow the sperm a longer time to achieve fertilization.
Finally, the oxytocin produced by sexual relations helps strengthen the bond between two people. So having sex at night is not a random occurrence. Nature has its reasons!
Read the full article here:
Why Do People Make Love at Night?