Women have a different biological clock than men and are often struggle to stay up late in the night because their day starts early.

The difference in circadian rhythms is also the reason why almost half of the women suffer from morning insomnia, struggling to go back to sleep once they are awake early in the morning.
The study also warns that majority of the women are permanently sleep deprived since they fight against the natural cycle and try to stay awake at least as long as their partners are awake but get up early in the morning.
Source-Medindia