A new study on the connection between wake-up times and heart disease shows that there is a positive relationship between these variables. I have two quick responses:
- This may be partly correlation. People who are chronically stressed are at higher risk for heart disease and would also have trouble sleeping.
- Lack of sleep can be causal as well. Sleep allows the body and mind to regenerate. A lack of sleep does not allow for sufficient regeneration which could then cause heart disease.