my own observations  see more morningness in Vegetarians

Further to Dr Verma's observation, I think that these may have an indirect relationship as the impact of diet on circadian rhythms is affected by a number of factors.

The literature seems to be very scarce regarding the relationship between morningness-eveningness, diet and health habits and only three studies found weak to moderate correlations with less healthy diets and eveningness (1-3). Nevertheless, because I didn’t have access to this papers, I cannot say if the design, dietary records and statistics are robust. On the basis of these studies (Europe and Japan), it would be probable to find positive correlation between being vegetarian (which is associated with healthy diets and better health habits in Europe but I don't know for India) and morningness.

However, there is still the question about what this could imply in terms of medicine and public health. I am personally skeptical when I read statement like “individuals displaying preference for timing of the daily activities late in the evening are more prone to smoking, greater alcohol use and binge drinking (4)”. It seems to me that there is a cultural confusion factor: most of the social activities implying smoking and drinking occurs late in the evening (e.g. parties). Similarly, I have the feeling that morningness is a priori seen as an healthy behaviour and thus people who wants to adopt healthy habits will include morningness in their behaviour change strategy in addition to reduce smoking, alcohol use and eating less healthy foods. Nevertheless I am not familiar with the circadian medicine field and might have missed some points.

Best regards

1- http://www.tandfonline.com/doi/pdf/10.3109/07420528.2014.911188

2- http://www.tandfonline.com/doi/pdf/10.3109/07420528.2012.699128

3- http://www.tandfonline.com/doi/full/10.3109/09637486.2011.560563

4- http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0114635

An owl becomes a lark by change of diet, is that possible?

There may be a relationship between diet with circadian rhythms. An example; ACTH is secreated in a circadian rhythm. Also, ACTH levels negativelt correleated with blood sugar.