Let there be light? This paper is concerned with the causal effect of the clock on diet, health, and health-related time use. To this end, I utilize a unique natural experiment: twenty years of clock reforms in Russia. The borders between the eleven Russian time zones have been frequently moved. Differently from existing papers, which focus on the transition to and from daylight saving time, I utilize permanent shifts in time zones. Analyzing the 1995-2015 period, I estimate both immediate and lagged effects of clock reforms, using both regional and individual data. The results are not uniform. On the one hand, Russians, especially in the south of the country, improve their habits with a later daylight: their diet is healthier, they lose weight, and are more physically active. Children are more likely to do sports every day and spend less time playing at home. Furthermore, Russians' weekly sleep is 25 minutes shorter for a one-hour shift toward a later daylight and almost 40 minutes shorter in the southern half of the country. However, the major problem with a later clock arises when its effect on disease and health problems is considered. In particular, in the north of the country, several diseases are more common with the later clock. Individual data reconfirms the positive relationship between the later clock and disease. Finally, I compare Russia with the United States, using the 2007 extension of the daylight saving time in America. Even though the two countries are not fully comparable in terms of the natural experiment they experienced, I construct a difference-in-differences setup in the United States. The results show that in the U.S., the later daylight is associated with a lower expenditure on fast food but with a higher expenditure on meat and baked goods. The American time use shifts with a later daylight toward more socializing and less relaxation.