Lower salt generally lowers blood pressure, but it turns out this may not apply in all instances. A mouse study suggests that a low-salt diet can increase the risk of hypertension if you have a disrupted circadian rhythm. Sleep disorders, shift work, disease, and aging are all potential signs of or triggers for circadian dysfunction.
A 24-hour blood pressure check may reveal that blood pressure is not falling, as it should, during the night. Nondipping blood pressure is estimated as high as 53% in patients being treated for hypertension. It may be that, for those with a disrupted circadian rhythm, the timing of antihypertensive medication should be different.
Pati, P., Fulton, D. J. R., Bagi, Z., Chen, F., Wang, Y., Kitchens, J., … Rudic, R. D. (2016). Low-Salt Diet and Circadian Dysfunction Synergize to Induce Angiotensin II–Dependent Hypertension in Mice. Hypertension, 67(3), 661–668. http://doi.org/10.1161/HYPERTENSIONAHA.115.06194