Better Call Saul‘s leading female character, the driven but overworked and underslept Kim Wexler (played by Rhea Seehorn) does a brilliant job of capturing the sudden and compelling nature of a microsleep.
What is a microsleep?
This phenomena occurs when your brain forces a brief intrusion of very light, transitional sleep (anywhere from a fraction of a second up to 10 seconds long) as the result of sleep deprivation. Causes of sleep deprivation included voluntary sleep restriction, insomnia, other sleep disorders, stress, and medication use.
Even when a person wishes to will themselves to stay awake, the brain (via the circadian system) has ways to override that will when the sleep-deprived individual reaches critical mass.
“Sleep drive” and “sleep pressure” both reference this mechanism, in which the brain determines that the body has been awake too long to maintain homeostasis (or biological balance across all body systems). It begins to force a period of sleep to preserve the built-in circadian cycles that a person might have tried to suppress.
Ultimately, the brain wins. Our circadian rhythms are that strong.
Actress Seehorn does a fantastic job of capturing the nuances of a microsleep in this clip. And yes, microsleeps really are this subtle. She’s reciting her talk for an upcoming meeting while she’s driving, then she slips into a blank stare, her chin slightly dips and softens, her eyes flutter and squint. The expression on her face suggests mild concern, like something isn’t quite right, but there isn’t any yawning or rubbing of eyes or other behaviors related to simply being tired. She has become so sleep deprived at this point that her body is long past this stage of warning her to get some sleep.
It’s important to note that people who are sleep deprived are rarely aware they are experiencing microsleeps, no matter where they are or what they are doing. They may admit to feeling distracted or preoccupied, or they might even perform functions with their eyes wide open while they have a microsleep.
Microsleeps are a key feature of drowsy driving
It’s one thing for a college student to have a microsleep while studying for an exam, and quite another to experience one behind the wheel of a moving vehicle.
After a long week of personal crises in late May 2014, I still faced the task of passing my board exam to become a Certified Clinical Sleep Health (CCSH) educator. I spent 2 days in a hotel studying for the test, which was out of town. Meanwhile, I still had to deal with intrusive thoughts about family and health matters, which ultimately fragmented my sleep.
When I sat down to take the 4-hour test, I distinctly recall waking up repeatedly in front of the computer terminal where I was supposed to be clicking on answers. My white board (what they give you to use while taking the test to work out equations or draw diagrams) had new random squiggles where my black felt tip pen had touched the surface after I’d slipped into yet another microsleep.
I lost count of how many times this happened.
The good news is, I passed, but that is only because I knew I had to go over every single question and answer to make sure I hadn’t clicked any in error. I used up almost the entire testing time in order to accomplish this; I must have taken that whole test three times before I decided I was ready to click Submit.
This is a stressful experience, for those who’ve not taken a supervised board exam. If you click Submit and your test results suggest a fail, then you have to take the entire test all over again (and these tests run around $350 each time). That means you have to take it all over again and pay a new fee. Certainly, worries about this were another reason why I didn’t sleep well beforehand.
The bad news is, I had to drive back to the hotel after that. But not to worry! Instead of driving, I reclined the seat in my car and took a nap before I hit the road. It was one of the easiest naps I’ve ever slipped into.
It might be argued that the majority of all drowsy driving accidents are preceded by these kinds of microsleeps.
Not everyone who drives drowsy is completely asleep, by the way. You can be functionally awake and still run yourself off the road. However, it’s also possible to drive with your eyes wide open and still be asleep, however fleetingly.
Driving (or performing any number of other physical tasks) with your eyes wide open is described by some as “automatic” behavior. It has been measured with success by way of EEG testing. Sleep-deprived subjects wore electrodes while driving (in a safe, controlled environment) and experienced distinctive shifts in brain wave patterns that exactly matched the patterns associated with normal sleep onset, except these sudden transitions from wake to stage 1 sleep occurred during driving tasks while their eyes were open.
Imagine a sleepy driver using cruise control on a wide-open highway. How conducive are those conditions for sleep? I can feel the warm cozy feeling of slipping into sleep mode just thinking about it! If you’ve ever fallen asleep in a car as a passenger, you know the feeling.
But you don’t have to be on cruise control to experience drowsy driving. You can be just as vulnerable as attorney Kim Wexler in Better Call Saul, who was in local daytime traffic practicing a vigorous intellectual exercise while driving to a meeting she is late for. Even the stress of being late to this critical meeting does not prompt enough adrenaline in her body to offset the coming circadian takeover that leads to her microsleep and concurrent accident.
I like the character, Kim Wexler. But please, don’t be Kim Wexler. Not like that.
Gratitude to the directors and producers of Better Call Saul at AMC for doing such a fine job of weaving this important scene into their storyline. And kudos, again, to Seehorn, for giving us all such an accurate (if terrifying) depiction.