Emergency Messaging at Night


After the huge tornado disaster in December, we were surprised to find out that tornadoes at night are roughly 2.5 times more deadly than daytime tornadoes.  And while there are lots of reasons offered for that difference, it seems that no one really knows why nighttime tornadoes kill more people. 

Whatever the cause, a lack of warning did not seem an issue in December.  As the the NYTimes reported: 

 …if anything went wrong before the storms hit, it was more a lack of response to warnings than a lack of information about the dangers. Severe weather warnings began on Thursday and were issued throughout Friday in a host of states. Sirens woke residents in some areas late Friday and early Saturday to warn them that a tornado was near and that they should take shelter away from windows.

Steven Strader of Villanova University put it  this way: “Adequate warning does not always ensure that people will take shelter, can take shelter, or know the quality of their shelter (home)…” 

Since some of the explanations for the higher mortality of nighttime tornadoes might also apply to other emergency situations at night, it got us thinking about the implications for nighttime emergency alerts. The explanations below don’t seem to be specific to tornadoes. They could affect the response to any alerts that are sent out at night.

1. Access to emergency alerts (do not disturb settings).

Most smartphones have “do not disturb” settings that silence notifications except from specific callers.  While we don’t know how prevalent this is, it appears that at least some smartphones will allow users to silence notifications from WEA alerts. 

2. Fatigue and response to emergency alerts.

Although it varies widely, many people are tired at night and fatigue is a known factor in impairing executive function

3. Sleep inertia.

Beyond simple fatigue is a phenomenon known as sleep inertia, which occurs when someone is woken from sleep. Sleep inertia’s symptoms include grogginess, impaired motor dexterity, decreases in cognitive ability and a sense of fatigue.  These symptoms can last 15-60 minutes after waking and even longer for some people, preventing folks from effectively processing the information in emergency alerts.  

4. The impact of alcohol.

About 30% of American adults average at least one drink per night, while 10% average an astonishing 10 drinks per day. Alcohol consumption is not limited to nighttime, of course, but many people don’t start drinking until after the workday.  Since it takes 2 hours to metabolize a single pint of beer, alcohol must be considered an important potential factor in processing emergency alerts. 

5. Darkness as a factor in interpreting nighttime alerts.

Although we couldn’t find any statistics, there is a lot of anecdotal evidence suggesting that people attempt to confirm some alerts at night by simply looking outdoors.  This is cited as one reason for excess tornado fatalities, since the darkness of nighttime makes it difficult to see funnel clouds, etc.  But the same might easily apply to other environmental hazards. 

6. Anxiety, vulnerability and nyctophobia.

Although most people grow out of their childhood fear of the dark, there’s no question that at least some people continue to feel increased levels of fear, anxiety and doubt at nighttime. And when the condition is severe, it’s called “nyctophobia”

7. Inability to get confirmation information.

It’s a well-documented fact that most people attempt to get confirmation of emergency information from multiple sources.  But when the alert comes in the middle of the night, there are fewer sources of such confirmation.  

Of course, tornadoes are not the only emergencies that can happen at night.  Wildfires, chemical leaks, explosions, and earthquakes are just a few of the situations we can think of that might trigger an alert sent at nighttime. 

Given the factors that can affect how messages are processed at night, what should emergency managers do to make nighttime alerts more effective in their communities?

1. Tell people to enable emergency alerts at night.

  • Suggest they check the Do Not Disturb settings on their phone to ensure that they allow Wireless Emergency Alerts.
  • Give them the caller IDs you use for emergency alerts and ask residents to include them on their list of “favorites”

2. Ensure that your messages are clear and compelling.

There are multiple reasons that people might not be able to understand your messages clearly, including fatigue, sleep inertia, and alcohol.  Since the average American reads at the eighth grade level under normal circumstances, you want to aim for something lower than that.  Dumb your message down and make it crystal clear using as simple language as possible.

3. Repeat messages.

People are looking for confirmation information and while you may not be able to put them in contact with their neighbors, “repetition is the mother of learning”.  

4. Set expectations (e.g. you won’t be able to see this coming, etc.)

If it’s applicable, let folks know they won’t be able to see outside and confirm what you’ve told them.  Just be authoritative and tell them what you want them to do. 

5. Provide links to confirming information.

Since people want confirmation, if you have access to another source – for example, something on the web – you can include links to that so they can get some other source that reinforces your message. 

6. Let them know about resources to give a sense of empowerment.

People feel more vulnerable at night, so if you can do it, let them know how they can get additional help or help themselves.  For example, if you’re issuing a “shelter-in-place” message, suggest they gather the items they might need like food, water, etc. in the area they would use for shelter. 

7. Tell them what to do.

More than anything else, be clear about what you want them to do, even when the situation is potentially ambiguous. As the book Emergency Alert and Warning Systems says:

People also want specific language that gives precise and non-ambiguous information about the area(s) at risk, how much time they have to engage in protective actions before impact, and the source of the message…. facts relating to the hazard need to be stated “authoritatively, confidently, and with certainty, even in circumstances in which there is ambiguity…explain that…experts agree on the protective actions people should take.

After reviewing this topic, it seems to us that more research needs to be done in this area, since there are many dangerous incidents that can happen at night and many circumstances that make nighttime emergencies different from daytime ones.  We’ve tried to identify the factors that can affect how your alerts might be received at night and how you can adapt to make them more effective.


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