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It's a safe bet that, when hurricanes hit, sleep health is not a top priority for residents of affected regions. But sleep disturbances are one of the most common health issues reported during and after catastrophic events. And, in research on natural disasters, including Superstorm Sandy, hurricanes Andrew and Katrina, and the 2011 Japanese earthquake (often referred to in Japan as the Great East Japan Earthquake), sleep quality has emerged as both a meaningful reflection and predictor of mental and physical well-being.

Good sleep in the wake of natural disasters has been linked to psychological resilience and positive health outcomes, while sleep disturbances appear to play a role in the development of PTSD, depression and poor immune function. By taking measures to promote sleep, we can help minimize the long-term health consequences of natural disasters. And, by paying attention to how survivors are sleeping in the aftermath of disasters, we can target people who may have a pronounced need for healthcare during times when services are likely to be stretched thin.

Surviving any type of disaster, natural or man-made can lead to trauma-related sleep problems and scary dreams. But, with natural disasters, physical displacement often creates additional barriers to a good night's sleep. "If your bedroom has been flooded, and you have to go to a shelter, the unfamiliar and uncomfortable environment can additionally impact your sleep," said Thomas Mellman, a professor of psychiatry and director of the Clinical and Translational Research and Stress and Sleep Studies Programs at the Howard University College of Medicine.

Shelter shuteye  

Are there any policies in place that enable survivors to get sleep during natural disasters? Well, FEMA guidelines stipulate that emergency shelters housing evacuees for longer than 24 hours have quiet, dimly lit sleeping areas and provide a minimum of 5.6 square meters — about 60 feet — of floor space per person. If shelters house evacuees for less than 24 hours, then sleeping areas aren't required.

The US Agency for International Development, which is responsible for providing civilian disaster relief in low-income nations, also mandates that shelters provide sleeping accommodations for evacuees. "Shelters are places of refuge and must not result in disaster to the occupants," states the USAID Shelter Management Guide. "Care must be taken to minimize overcrowding and occurrences of unhealthy environments." But USAID imposes a lower minimum floor-space requirement, allotting 40 square feet per person.

In practice, however, a shortage of shelter space can make guidelines hard to follow. After Harvey hit, Houston's George R. Brown Convention Center held more than 9,000 evacuees, nearly two times its capacity. As a result, personal space and cots were on short supply. As USA Today reported, regarding an 18-year-old evacuee:

"Last night I slept on the hard floor and used a towel as a pillow,” he said, pointing to cardboard that’s his bed. “They said there are no cots. Since last night we’ve been asking for a crib for the baby and we still don’t have one."

The difficulty of sleeping in over-crowded shelters is backed up by research. For both practical and ethical reasons, it's tough to perform studies during crises. But a team of researchers from Japan managed to collect data from more than 9,000 evacuees living in 30 emergency shelters after the Great East Japan Earthquake. Researchers obtained information about evacuees' sleep from medical clinics set up in the shelters. Their findings, published last year, showed a higher daily incidence of disturbed sleep in crowded shelters, compared to roomier ones. Researchers determined that evacuees faced a heightened risk of disturbed sleep if they had any less than 5 square meters of personal space, a conclusion that lends credence to the FEMA guidelines.

"This novel finding," researchers wrote, "would assist public health authorities in establishing appropriate evacuation plans and facilities to prevent the incidence of sleep disturbance among evacuees ... crowding at the shelter is potentially a modifiable factor that can be avoided by appropriate evacuation planning."

A downward spiral

It's reasonable to wonder, however, how much it really matters if people get less-than-stellar sleep in the immediate aftermath of a storm. After all, humans are wired to function in crisis mode. And, if there's a hierarchy of disaster-time needs, a full night's sleep ranks somewhere below escaping two-story-high floods and finding shelter. 

But, there are also good reasons for public-health authorities and relief organizations to help disaster evacuees get sleep: In the aftermath of a traumatic event, sleep disturbances alone are thought to play a role in the onset of PTSD and other afflictions. That means that, not only do sleep problems reflect a survivor's state of health, they can also be part of the reason that a survivor develops a mental disorder down the line. And, as the authors of the shelter-crowding study wrote the emergence of new, longterm mental-health problems "might result in significant burdens on the health care organizations at disaster-affected areas, which are typically already suffering from a shortage of medical resources."

In one study on Hurricane Andrew, the Category 5 storm that ravaged Florida in 1992, Mellman and colleagues gathered data on sleep and mental health during the recovery phase (meaning 6-12 months after the storm). By this point, most survivors had left shelters. But they were dealing with plenty of other storm-related stressors, such as compromised sleep environments, lack of electricity, generator noise and safety-related fears, that left them with sleep problems.  

Mellman's team found a bidirectional relationship between sleep and disaster-related psychiatric symptoms: People with a pre-storm history of poor sleep and scary dreams were more likely than other survivors to struggle with symptoms of PTSD and depression after Andrew. And, going the other way, people with a history of psychiatric symptoms were especially likely to face post-Andrew sleep problems. Researchers concluded that a tendency to experience poor sleep and nightmares marked a vulnerability to developing PTSD following a disaster.

In attempting to explain the association between PTSD symptoms and impaired immunity, researchers found one link: the onset of new sleep problems.

It's worth noting that sleep problems become more likely after natural disasters for both adults and children. More than two years after Hurricane Katrina, one study found, about half of children (in a group of 191 who'd endured the storm) reported sleep disturbances. That's a considerably higher incidence of sleep problems than you'd expect to find in children, according to Carl Weems, a researcher at Iowa State University who co-authored the study with Mellman. 

In a different study, sleep problems following Andrew were also linked to impaired immune function. In this case, researchers collected questionnaires and blood samples from residents of neighborhoods damaged by Andrew between 1-4 months after the storm hit. They found a significant association between PTSD symptoms and lower counts of natural killer cells. These immune cells play an important role in helping us fight infection and developing adaptive immune responses to new environments. Low NKC counts have been linked to cancer.

In attempting to explain the association between PTSD symptoms and impaired immunity, researchers found one link: the onset of new sleep problems. They assumed that other, undetermined factors (aside from sleep) played a role in the PTSD-immunity link, too.

The flip side 

The relationship between post-storm sleep disturbances and subsequent health issues, however, is only half of the story. Sleeping well in the wake of a natural disaster, according to a 2017 study, appears to have a protective effect on health. Following the Japan Earthquake, researchers from Fukushima Medical University surveyed more than 30,000 people living in evacuation zones about their socioeconomic status and health, as well as several lifestyle factors, such as sleep habits, alcohol consumption, exercise and community engagement.

They focused on socioeconomic changes because it's common, and often unavoidable, for disaster survivors to lose jobs and change living situations. And these types of disaster-induced changes have been linked to poor health. So, in this study, researchers wanted to see if there were any lifestyle factors that protected survivors against the health decline associated with socioeconomic hardship.

Sleep, it turned out, made a difference. Both income loss and changes in living conditions were linked to poor health. But, across the board, people who were satisfied with their sleep reported being in better states of health. So, in some way, people who slept well withstood the deterioration of health that typically accompanies the loss of jobs and homes. Improving sleep, researchers reasoned, may help ward off the undesirable health consequences of enduring a natural disaster.

Taken together, these studies show that, as Mellman put it, "healthy sleep contributes in important ways to positive adaptation, whereas disruptive sleep, or avoidance of sleep, can increase the likelihood that someone will have trouble with post-traumatic stress or depression, or even the physical health consequences of a disaster." 

Researchers brought up the concept of "perceived benefit," in which people who believe they've somehow benefitted from a disaster have an easier time recovering from it than those who don't perceive any benefit from the experience.

It might also make sense to consider how survivors sleep before natural disasters. Survivors' pre-storm sleep habits, according to a 2015 study, predict their levels of psychological resilience to the storm-related stressors they'll later encounter. Researchers from institutions including The University of Connecticut Health Center and Texas Health Care System examined the sleep quality, mental health and emotional stability of young, low-income women who'd survived Hurricane Ike, which hit Texas in 2008. They surveyed the women several times, from before Ike hit through a year afterwards.   

During the storm recovery period, good sleepers (based on pre-Ike assessments) were considerably less stressed than poor sleepers — and even less stressed than they'd been before the storm. To explain this finding, researchers brought up the concept of "perceived benefit," in which people who believe they've somehow benefitted from a disaster have an easier time recovering from it than those who don't perceive any benefit from the experience. The worse the disaster is, the greater the perceived-benefit effect is.

It's possible that sleeping well sets people up for the perceived-benefit effect, either by modulating their negative emotional responses to stress or by maximizing their ability to use effective coping strategies to deal with it. In their analysis, researchers accounted for the impact of hardship and property damage on study participants' sleep. In other words, as researchers explained, survivors' sleep quality "was not simply an acute state reflecting the trauma of Ike. Sleep quality, even after the hurricane, seems to primarily reflect women's long-term experiences." 

Screening for sleep problems

Across the board, studies on sleep and natural disasters urge the inclusion of sleep questions in medical screenings for survivors and, in some cases, for workers dispatched to relief efforts. Back in 1995, for instance, Mellman and colleagues wrote in their Hurricane Andrew study that "assessing for sleep complaints could provide a practical focus for screening populations exposed to traumatic events." 

Public-health authorities have not heeded their recommendations.

The CDC provides guidelines for crisis-related medical screenings. The "Natural Disaster Morbidity Surveillance Individual Form," for instance, is intended for use in acute care facilities, meaning hospitals and shelters with medical staff, to gather information about evacuees' health conditions. The form, which includes questions on physical and mental health symptoms, does not mention sleep once.

There is also no mention of sleep in the pre-and-post-disaster medical-screening guidelines for relief workers. These screenings, per the CDC website, are intended to:

... identify those who need further medical attention, not necessarily to definitively diagnose or treat based only on information provided through the screening ... Through screening, adverse effects in individuals can be recognized in a timely way to provide intervention for the individual, while identifying potential risks to others in the same population.

We reached out to the CDC for comment and will update this story if they respond. 

Some fact-sheets and online resources geared toward natural-disaster survivors do, however, bring up sleep. The Substance Abuse and Mental Health Services Administration, for instance, mentions sleep in tip-sheets aimed at survivors of traumatic events and disaster first-responders, respectively. "Maintain a healthy diet and get adequate sleep," for instance, are listed as responder self-care techniques. And the National Institute of Mental Health mentions sleep in its overview of coping with traumatic events. But you won't find more than a bullet point devoted to sleep health anywhere in the sphere of .gov resources for disaster survivors. 

And, for now, Mellman doesn't think sleep will become a healthcare priority during natural disasters. "I think it's important that we seek to provide comfortable sleep environments to the extent that it's possible. But, realistically, I don’t think we have the mental health resources to provide counseling or therapy to everyone affected by a natural disaster who has some disruption of their sleep."

So survivors may need to take it upon themselves to know when sleep problems merit medical attention. "If a person continues to have disturbed sleep in the aftermath of a disaster, even as, structurally, things are getting back to normal," said Mellman, "then I would advise some type of intervention involving medical or mental-health services. But even just talking about things that are disturbing that they tend to push back out of their minds, but then show up in dreams, tends to be helpful, whether that’s with a friend, a professional or a relative."