Reacción a "Not changing the time in summer or winter in the US would reduce strokes and obesity, according to a study"

Is the study of good quality?

‘Methodologically, it is consistent and reasonable. If we base ourselves on pure epidemiological theory, we are looking at an ecological study that provides estimates but cannot establish causality. However, these studies are necessary for further research and provide us with essential information on a very large population group that could not be obtained with other types of methodological designs.’

What does it add to previous research?

"The authors use light exposure simulation models based on a mathematical model to estimate the possible impact of different time policies in the US. Although this is an issue that has been discussed for several years due to the potential health problems associated with this time change due to circadian misalignment, this study provides valuable information through mathematical models of the possible consequences in relation to obesity and cardiovascular disease. It also indicates the best time schedule for the US population. These results are additional evidence to be taken into account by politicians."

What are the implications for the time change in Spain?

"The exact data cannot be extrapolated to Spain due to differences in latitude, time zone, time patterns, socio-demographic and health data, among others. However, a similar model could be applied to analyse what would happen in our country. One of the main differences with Spain in relation to this study is that in our country, the best and least popular time for the population in general is winter time. It should be remembered that our time zone is not the correct one and winter time would be the one that most closely resembles the time zone in which we find ourselves. The health findings seen in this study could be similar to those we might have in our country if a similar study were conducted due to the circadian disruption caused by biannual time changes.

What are its limitations?

"These factors are difficult to integrate into a study of this type, but some of the limitations would be:

• Use of an idealised light exposure scenario with a fixed pattern that does not incorporate seasonal changes.
• Possible variations in subjects' schedules, such as shift work, differences between weekdays and weekends, and other behavioural patterns (difficult to integrate these individualities) are not included, and how this may affect light use (natural or artificial).
• To determine health data, they only use intermediate chronotype data, when evening types have the most associated problems.
• Factors such as age, rural or urban environments, disease patterns, etc. are not taken into account.
• Methodological design (indicated above).