Middle-aged and older adults who sleep less than 6 hours per day and take longer midday naps are more likely to develop hypertension and CVD, with slight variations for men vs. women, researchers reported.

“Siesta is a prevalent lifestyle in many countries, including China, and according to the data from [the] Chinese Center for Disease Control and Prevention, 39.3% of Chinese adults aged 15 to 69 years take siesta regularly and the rate of siesta was the highest among people aged 60 to 69 years,” Ling Lin, MM, of the department of emergency nursing at Fujian Medical University Union Hospital in Fuzhou, China, and colleagues wrote in the study background. “Too long [a] siesta may decrease the sleep duration at night and affect the total sleep duration of people, indicating that the percentage of siesta in the total sleep duration may be associated with the risk of hypertension or CVD. Whether the ratio of siesta duration in the total sleep duration was associated with the occurrence of hypertension or CVD was still unclear.”

Longitudinal sleep data

Lin and colleagues analyzed data from 7,604 middle‐aged and older adults with sleep data and without hypertension or CVD at baseline, using the China Health and Retirement Longitudinal Study (CHARLS) database, a nationally representative longitudinal survey conducted in mainland China between June 2011 and March 2012. Median follow-up was 6.5 years; participants were followed for up to 3 years with questionnaires, with follow-up discontinued when an outcome event (hypertension or CVD) was observed. Researchers assessed associations of siesta and siesta ratio with incidence of hypertension and CVD.

The findings were published in Clinical Cardiology.

At the end of follow-up, 2,075 participants had hypertension and 986 participants had CVD.

Researchers found that, compared with a sleep duration of 6 to 8 hours, total sleep duration of less than 6 hours was associated with increased risk for hypertension, with an OR of 1.168 (95% CI, 1.023-1.335). A siesta ratio of at least 0.4 was similarly associated with hypertension risk, with an OR of 1.712 (95% CI, 1.129-2.594).

Sex-based differences in sleep time, CV risk

Among men aged 60 years and older, a siesta ratio of at least 0.4 was associated with higher risk for hypertension, whereas a total sleep duration of less than 6 hours was correlated with elevated risk for hypertension in men younger than 60 years.

Participants with a siesta duration of less than 30 minutes were more likely to develop CVD (OR = 2.053; 95% CI, 1.323-3.185). Among women aged 60 years and older, a sleep duration of less than 6 hours at night was associated with increased risk of CVD, whereas a siesta duration of less than 30 minutes and sleep duration of less than 6 hours at night was associated with CVD risk among women younger than 60 years.

“A longer daytime nap may lead to the elevation of evening cortisol levels and then increase the blood pressure levels,” the researchers wrote. “A high ratio of siesta suggested a long duration of siesta and a shorter duration of the sleep at night. The mechanisms of these might be because a longer duration of siesta may result in insomnia or low quality of sleep at night. Increasing studies indicated that a better night sleep is essential for the health of people.”

The researchers noted that the findings might provide a reference for midday napping and total sleep duration in people aged 45 years and older and said longer sleep at night vs. midday napping may be recommended.

The findings follow similar research published in July in Hypertension. As Healio previously reported, adults who reported taking frequent daily naps had greater risk for essential hypertension and stroke compared with those who never or rarely nap, likely due to poor sleep at night.