Could sleep be the new frontier of feminism? Women are more prone to poor-quality sleep because our body clocks are two hours ahead of men's, according to new research. Scientists in Canada found that women were more tired than men at night and more alert than men in the morning. But many of us are still going to bed at a time that better suits our boyfriends and husbands. One consequence is that women are more prone to insomnia, sleeping badly and feeling tired in the morning. The scientists, whose paper is published in the journal Proceedings of the National Academy of Sciences, wanted to find out why women are 50% more likely to have problems sleeping at night than men. They analysed the sleep patterns and alertness of 15 men and 11 women for three days, paying attention to their circadian clocks, which control our sleep-wake cycles so that they are in tune with the day-night cycle, making us feel tired and alert at the right times of day. The women studied were at two phases of their menstrual cycle, which was relevant because previous research shows this affects patters in our body temperature and sleep. During the 72-hour study, participants were kept awake for an hour and allowed to sleep for an hour if they wanted, on-and-off. The scientists then analysed their alertness, core body temperature and levels of the sleep hormone melatonin, as barometers of their circadian rhythms. The researchers concluded that, because women were less alert at night, they may be less biologically suited to night work. The study is further evidence that people can have very different circadian rhythms despite following similar sleep-wake patterns. Teenagers, for instance, are biologically programmed to stay awake later and sleep later. If this isn't a good excuse for an early night tonight, we don't know what is.