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• Rapid eye movement (REM) sleep is necessary for the body to repair itself
• People with lower levels of REM sleep were found to have higher mortality
• We should get the right amount of sleep – seven hours recommended for adults

Deep sleep is essential for good health, and too little of it may shorten your life, a new study suggests.

REM (rapid eye movement) sleep is when dreams occur and the body repairs itself from the ravages of the day. For every 5% reduction in REM sleep, mortality rates increase 13% to 17% among older and middle-aged adults, researchers report.

“Numerous studies have linked insufficient sleep with significant health consequences. Yet, many people ignore the signs of sleep problems or don’t allow enough time to get adequate sleep,” said lead researcher Eileen Leary. She is a senior manager of clinical research at Stanford University in Palo Alto, California.

“In our busy, fast-paced lives, sleep can feel like a time-consuming nuisance. This study found in two independent cohorts that lower levels of REM sleep were associated with higher rates of mortality,” she said.

Ways to optimise REM

How REM sleep is associated with risk of death isn’t known, Leary said. Also, this study couldn’t prove that poor REM causes death, only that it’s associated with an increased risk of dying early.

“The function of REM is still not well understood, but knowing that less REM is linked to higher mortality rates adds a piece to the puzzle,” she said.

It’s still too early to make recommendations about improving REM sleep based on this study, Leary said.

“As we learn more about the relationship, we can begin looking at ways to optimise REM. But that is outside the scope of this project,” she said.

For the study, Leary and her colleagues included more than 2 600 men, average age 76, who were followed for a median of 12 years. They also collected data on nearly 1 400 men and women, average age 52, who were part of another study and were followed for a median of 21 years.

Reliable predictor of mortality

Poor REM sleep was tied to early death from any cause as well as death from cardiovascular and other diseases, the researchers found.

REM sleep’s links to mortality were similar in both groups.

“REM sleep appears to be a reliable predictor of mortality and may have other predictive health values,” Leary said. “Strategies to preserve REM may influence clinical therapies and reduce mortality risk, particularly for adults with less than 15% of REM sleep.”

Previous studies have focused on total sleep time and have shown that both not enough total sleep and too much total sleep can be associated with increased risk of dying early, said Dr Michael Jaffee, an associate professor of neurology at the University of Florida in Gainesville.

“When we sleep, we go through different stages to include REM sleep. REM describes our eye movements during this stage and is also the state associated with when we have dreams,” he said.

This study shows that it is not just total sleep time that may be important, but assuring the right balance of the different stages of sleep, said Jaffee, who co-authored an editorial that accompanied the study.

Proper sleep time

Neurologists need to look for conditions affecting patients, such as obstructive sleep apnoea, that can reduce REM, and doctors should also be aware that certain medications they prescribe can reduce REM, he said.

The study also opens up additional avenues for research to determine if scientists should focus on treatments that affect not just total sleep but target sleep stage balance, Jaffee said.

“This study shows yet another reason for the importance of proper sleep time – recommendations for adults is seven hours – and a good balance of sleep stages by assuring that any possible conditions, such as obstructive sleep apnoea, that can cause a reduction in REM to be evaluated and managed,” he said.

“Anyone with difficulty with sleeping or with loud snoring can benefit from discussing this with their physician,” Jaffee added.

The report was published online on 6 July in JAMA Neurology.

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• Trigger warnings at the beginning of books or films aim to prepare previously traumatised readers or viewers for potentially upsetting material
• A new study found that this precaution was not helpful to trauma survivors
• The researchers concluded that a prior warning did not lessen the impact of the disturbing material 

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Trigger warnings are meant to alert trauma survivors about unsettling text or content that they might find potentially distressing.

But these words of caution at the start of films or books may provide no help at all – and might even hamper a traumatised person’s ability to grapple with deep psychological scars, a new study reports.

“We found that trigger warnings did not help trauma survivors brace themselves to face potentially upsetting content,” said lead researcher Payton Jones, a doctoral candidate in clinical psychology at Harvard University. “In some cases, they made things worse.”

Trigger warnings seem to increase the extent to which people see trauma as central to their identity, which can exacerbate cases of post-traumatic stress disorder (PTSD) in the long run, Jones and his colleagues found.

Some real soul-searching

“We found evidence that trigger warnings increased the extent to which trauma survivors saw their worst event as central to their life story,” Jones said. “Seeing trauma as central to one’s life is not a good thing.”

The study’s results are strong enough that they should provoke some real soul-searching about who’s really being helped by trigger warnings, said Guy Boysen, a professor of psychology at McKendree University in Lebanon, Illinois.

“It’s a pretty convincing argument that in the population that trigger warnings are supposed to be for, it’s not really doing much,” Boysen said. “It’s time in this research area to flip the question and ask not whether trigger warnings work, but is there any population in which they do anything?”

Previous studies on trigger warnings have had similar findings, but have been criticised because participants were from the general public and not specifically people with a history of trauma, said Boysen, an expert on the topic.

Where did trigger warnings originate?

The concept of trigger warnings evolved from work on PTSD, a condition in which reminders of trauma cause some to experience extreme emotional reactions, Boysen said.

Online discussion groups for survivors of sexual trauma came up with the idea of providing warnings in advance, so people could talk about their experiences without causing pain in others, the researchers said in background notes.

Since then, the concept has flourished. About half of all college professors told National Public Radio in a 2016 survey that they’d used trigger warnings to prepare students for potentially difficult material.

However, the practice has been adopted without any real research to confirm whether it actually helps, Jones said.

To test the effectiveness of trigger warnings, the researchers recruited 600 people who’d been exposed to a traumatic event – actual or threatened death, serious injury, or sexual violence.

Participants were split into two groups. Both read a series of literature passages that ranged from neutral to mildly distressing to markedly distressing.

The only difference was that one group received trigger warnings prior to reading distressing passages, while the other did not. Participants rated their emotions after finishing each passage, and also completed a series of psychological questionnaires at the end.

Overall, both groups appeared to react similarly to the passages. Neither seemed to be spared the emotional impact of reading the text, the researchers said.

Avoidance doesn’t help

But people given trigger warnings were more likely to express the belief that their trauma is an essential part of a survivor’s life story – something that won’t help them overcome their trauma, Jones said.

According to Boysen, “Avoidance is bad. The reason people don’t get over their phobias and traumas and fears is because they don’t allow themselves to be exposed to reminders of them or the things themselves, and that just increases their symptomology.”

Jones said the report is “one of the very first studies to test whether trigger warnings work as intended. The key takeaway for me is not that trigger warnings are ‘bad,’ but that for many years we have been implementing a policy for trauma survivors without testing whether it is actually helpful or harmful.”

Boysen suggested that trigger warnings might not work as intended because there’s simply no way to make them specific enough in a general setting.

He gave the example of a person who has been robbed at gunpoint in their own home by burglars.

“What is the trigger going to be for that? Is it going to be seeing a person who looks like that, is it going to be talking about guns, talking about robbery? It could be anything, right?” Boysen said.

Useful on an individual basis

“The triggers for things that might lead to automatic distress are so diverse, and so individualised, it’s impossible to predict in a general way what’s going to be triggering for people, because it’s 100% totally unique to that person,” Boysen added.

While generalised trigger warnings don’t appear to help, Boysen said they still could be useful on an individual basis – for example, if a student with a solid grasp of their trauma trigger lets a professor know in advance what type of content could cause distress.

“That’s a different thing, because the teacher then has more of a specific idea of what could be effective,” Boysen said.

The new study was published recently in Clinical Psychological Science.

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