If you have the luxury of a regular bedtime, there are many other factors (no overwork, stable life - at least so that you have control of when/where you sleep -, and lack of insomnia, for starters) that can explain this - not the regularity or the time itself.

I love sleep studies. There seems to be so much more we could learn. I wish this one was deeper (or perhaps the story isn't giving the full details).

> The link persisted after adjustment for sleep duration and sleep irregularity.

> The researchers tried to control for other factors known to affect a person's heart risk, such as their age, weight and cholesterol levels, but stress their study cannot prove cause and effect.

This study seems very shallow. Of course we can't prove cause/effect but it didn't think to account for other choices that people who go to bed between 10-11 make differently than those who don't. Typical to consider physical state (age, weight, cholesterol levels)--but these are lagging indicators--behaviours are leading ones. Another good factor to consider would be stress. Are behavioral factors not used because they are self reported and conclusions would be of the form "those who report they do ... are more/less likely ...." Ironically going to bed 10-11 is just such a self reported behavioral factor.