There was a study done last month published in the Proceedings of the National Academy of Sciences about the differences in circadian rhythm between men and women. Our circadian rhythm is the 24 hour cycle that controls many of our bodily functions, including when we sleep.
For this study, the researchers observed the natural circadian cycles of men and women in a controlled sleep lab over 2 to 6 weeks. The results showed individuals circadian rhythms ranged from about 23.5 to 24.5 hours, and was unaffected by age. The circadian clock of women averaged about 6 minutes less than the men, and the women were 2.5 times more likely than the men to have cycles shorter than 24 hours.
The researchers do not know why women's circadian rhythm would be shorter than men's, but it could be related to female estrogen levels.
A circadian rhythm that is short could explain in part why some women may have difficulty maintaining sleep and early morning awakening. It also could mean that women might get sleepy earlier than men. Unfortunately, there isn't anything that can be done to change the length of your circadian rhythm. Practicing good sleep hygiene and listening to your body will help you sleep better.