Reducing sleep length over two consecutive nights leads to less healthy vascular function and impaired breathing control, according to a new study by Keith Pugh, Shahrad Taheri, and George Balanos, of the University of Birmingham in the United Kingdom.

The researchers have worked with eight healthy adult volunteers between the ages of 20 and 35 to date. For the first two nights of the study, the researchers had these volunteers sleep a normal night of eight hours. Then, rather than restrict their sleep completely, the researchers instead had them sleep only four hours during each of three consecutive nights.

Each of these volunteers underwent tests to see how well their blood vessels accommodate an increase in blood flow. Following the first two nights of restricted sleep, the researchers found a significant reduction in vascular function compared to following the nights of normal sleep. However, after the third night of sleep restriction, vascular function returned to baseline, possibly an adaptive response to acute sleep loss, study leader Pugh explains.

In other tests, the researchers exposed subjects to moderately high levels of carbon dioxide, which normally increases the depth and rate of breathing. However, breathing control was substantially reduced after the volunteers lost sleep.

The researchers later had these volunteers sleep 10 hours a night for five nights. After completing the same tests, results showed that vascular function and breathing control had improved.

Pugh notes that the results could suggest a mechanism behind the connection between sleep loss and cardiovascular disease. “If acute sleep loss occurs repetitively over a long period of time, then vascular health could be compromised further and eventually mediate the development of cardiovascular disease,” he explains.

Similarly, the loss of breathing control that the researchers observed could play a role in the development of sleep apnea, which has also been linked with cardiovascular disease.
Pugh adds that some populations who tend to report sleeping shorter periods, such as the elderly, could be at an even higher risk of these adverse health effects.

The team discussed the abstract of their study, entitled “The Effects of Sleep Restriction on the Respiratory and Vascular Control,” at the Experimental Biology 2013 meeting. The findings are being presented at a scientific conference and should be considered preliminary, as they have not undergone peer review.