If you or a family member or friend have had to spend time in the hospital lately, you may recall being awakened at 2 AM to take your vital signs. Hospitals have been routinely checking their patients' vital signs every four hours since 1893 — two years before X-rays were discovered. Is it possible that doing so is nothing more than a medical anachronism?

A new study suggests that it might be.

The practice evolved for a good reason. A patient's vital signs (pulse, blood pressure, temperature and respiratory rate) offer an important window onto their health and can tell healthcare workers when a patient is in need of immediate medical attention.

But you can't get vital signs from a sleeping patient. Waking up patients to take their vitals makes their already fragmented sleep even more fragmented. Sleep is an important part of the healing process, and hospitals are already noisy, difficult places to sleep.

What would happen if hospitals stopped taking overnight vitals and let their patients sleep through until morning?

The researchers looked at over 54,000 patients of a 550-bed hospital using a modified early warning score, better known as a MEWS score. MEWS is designed to show which patients are highest risk and likely to need substantial medical care shortly.

Researchers found that 45% of the hospital patients were in the lowest risk category (MEWS 1 or less) and unlikely to need much medical attention in the next 24 hours. Yet these patients' vitals were taken just as often as those of patients with MEWS 7 or higher, patients who were 30 times more likely to suffer an adverse event in the next 24 hours.

When it comes to checking their vitals, high-risk patients are being treated exactly the same as low-risk patients. And that makes no sense.

The study is merely preliminary. It doesn't show what would happen to low-risk patients if their overnight vitals weren't taken, if their health would suffer or not. It merely suggests that these patients might benefit more from getting a good night's sleep than from being awakened so that their vitals can be taken.

It will take more studies to confirm this idea, but this study is a starting point to answering the question of whether overnight vitals for everyone is evidence-based medicine or not, a question that too few people have been asking.

Letting low-risk patients get their sleep also would free up nursing time that might be better spent elsewhere.

Those who bemoan the slow rate of institutional change and think this will never happen in their lifetime need only look to the case of improvements to the hospital gown for hope. If hospital gowns can change with the times, there's no reason to think that overnight vital sign checks can't too.

An article on the study was published online before print by JAMA Internal Medicine.