Her doctors diagnosed her with something called idiopathic hypersomnia. Anna interpreted this mouthful as “she sleeps a lot and we don’t know why.” It seemed like she was the only one with this condition. For narcolepsy, a disorder in which people experience overwhelming sleepiness, support groups existed. There were even arty movies depicting people with narcolepsy. But who had heard of idiopathic hypersomnia?

  When Anna came to Emory in the summer of 2005, she first underwent an overnight sleep study. Petite, slim, and not yet thirty, she was unlikely to have obstructive sleep apnea, usually assumed to be more common among older overweight men. Her overnight study confirmed that she did not.

  The results of a test the next day, when she was asked to take several naps, were more illuminating. This was Anna’s first Multiple Sleep Latency Test (MSLT), but she would grow used to being examined in this way. Beforehand, a technician glued electrodes to her scalp and placed more probes on her eyelids, face, and legs.

  Coincidentally, a jackhammer was rattling outside that day as part of a construction project. She wondered whether that was part of the test but had no trouble dozing off. For each of five naps, she fell asleep quickly.2 The average delay was less than three minutes: the “twilight zone” of sleepiness. A healthy person will take at least ten minutes to fall asleep on average, if they manage to do so all five times.

  During her naps, Anna did not enter REM sleep—the rapid-eye-movement dreaming phase. This meant that she probably did not have narcolepsy, which is rarer than obstructive sleep apnea. People with narcolepsy tend to enter REM sleep soon after a nap begins. In addition, people who have the more distinctive form of narcolepsy, narcolepsy with cataplexy, can experience muscle weakness when they have strong emotions. Anna has never experienced this symptom.

  “I was told that I couldn’t have narcolepsy, because I didn’t fall out and collapse,” she said. Her doctors looked for factors that would explain her sleepiness, such as thyroid or liver problems or other metabolic oddities. Although her iron levels were a bit low, nothing stuck out. The lack of any other explanation meant that her doctors arrived at a diagnosis of idiopathic hypersomnia, abbreviated as IH.

  As an initial effort at treatment, her doctors prescribed the same stimulants that someone with narcolepsy might receive. No rigorous clinical studies had been performed to test whether anything was effective against IH, and there were no FDA-approved drugs for the indication.3 Anna was first given the “smart drug” modafinil, which is supposed to be gentler than what came next: amphetamines. For a while, these medications helped her make it through the day. But to sustain the effects, her doctors had to increase the doses. They ended up giving her enough to make her feel twitchy and uncomfortable. She lost weight and developed high blood pressure and a “somewhat erratic sleeping pattern,” so she was advised about keeping a regular sleep schedule.

  Something within her body was resisting the stimulants. Although Anna took a slow-release form of amphetamines at bedtime, her roommate had trouble waking her and said that she sometimes appeared confused. She began experiencing crashes, in which she would sleep for more than thirty hours at a stretch. It happened every few months, but by the beginning of 2007, it increased in frequency to every week. The longest crash lasted for more than fifty hours. “That was the scary part,” she said. “If I went to bed, I didn’t know if I’d fall off the map and wake up two days later.” In April, she almost slept through an important hearing. It prompted her to take leave from her job, troubling for an ambitious young lawyer. She and her caregivers had six months to figure out what was going on, after which a formal disability determination would be necessary.

  Anna kept a photo from this time period, one in which she’s lying in a hospital bed smiling and wearing a T-shirt for the fictitious band Spinal Tap. In this uncomfortable procedure, known formally as lumbar puncture, her doctors obtained a sample of her cerebrospinal fluid, which surrounds the brain and spinal cord. The procedure represented a way to probe what was going on in her brain without slicing into it. Sampling her spinal fluid allowed her doctors to definitively rule out narcolepsy and to discover something else.

  The anesthesiology researcher Andrew Jenkins tested Anna’s spinal fluid and found that it contained a substance that behaved chemically like benzodiazepines, the class of drugs that includes Valium and Xanax. Doctors use some benzodiazepines to keep people relaxed during medical procedures. According to Jenkins, Anna had a level of sedative-like stuff in her body comparable to someone undergoing a colonoscopy or having her wisdom teeth removed—all the time.

  The presence of a benzodiazepine-like substance in her body was why her doctors, led by the neurologist David Rye, wanted to try the antidote: flumazenil. Several years before, Rye had treated a couple patients with similar symptoms with flumazenil. It woke them up, but the effect wore off quickly. Flumazenil was something that anesthesiologists or emergency room physicians usually had, but in tiny amounts. Its manufacturer had stopped producing it, and it was not approved by the FDA for any purpose besides its role as a benzodiazepine countermeasure. On top of that, in a fraction of the cases in which flumazenil was used, there were reports of panic attacks, seizures, even cardiac arrest.4 Still, it was worth a try. “At that time, I had no dependents; it was just me, so I felt I could afford to take a risk,” she said. “And this disorder was threatening to take away my career and even my brain.” Anna said that when the researchers found the unusual chemical activity in her spinal fluid, she felt a sense of relief; she had been worried that she was either “lazy or crazy.” Before the flumazenil experiment, she was examined by psychiatrists twice, to check for the possibility that she was depressed or inventing her symptoms. Her parents had approached a neurologist outside Emory, who cautioned that she was probably taking drugs recreationally. With her family, Anna managed to keep a sense of humor about her situation. “My brothers turned it into a joke,” she said. “We lobbied for naming it the ‘Sumner stupor,’ because stupor is what it felt like. The only thing that could wake me was a dog’s tongue up my nose.”

  SLOW UNDERCURRENT

  Anna grew up as the daughter of a lawyer and a judge outside the small town of Winona, Mississippi. Articles in the local newspaper describe her playing tennis, riding horses, and getting good grades. Her elevated need for sleep began to emerge in her last year of high school, when she started taking naps after morning chapel. At Princeton, she told herself that she was working hard and her body needed extra rest. She was hiding how much sleep was encroaching upon her life. She would choose naps over eating lunch, exercising, or time with friends. Every evening, she returned to her dorm room after dinner to go to sleep for a couple hours. If her parents called, she had her roommate tell them she had gone to the library. Even so, they noticed that when she came home on holidays, she spent most of her time in bed.

  At some American universities, students joke that they are forced to pick two of three things: good grades, a social life, or enough sleep. To observers, it might have looked like Anna did not have to sacrifice. She joined a sorority and social clubs and still ranked at the top of her class. Over the years, Anna kept a list of events she slept through: a date, a concert, a friend’s wedding. She hid them well; when her sleep disorder was eventually diagnosed, friends told her they thought she had avoided some gatherings because of social anxiety.

  After graduation, Anna moved to Bangkok to teach English. In a hot climate, taking siestas didn’t seem too strange. Then she spent a winter in London, working on a novel. The weather was different, but her sleepiness stayed with her. Before she applied to law school, she underwent tests to rule out causes of fatigue such as mononucleosis or anemia. At Duke, Anna coped well enough with naps between classes; she then clerked for a federal judge in New Orleans. “In law school, as long as you show up for your commitments, nobody will bother you,” she said. “I never liked coffee, but I did drink lots of Diet Coke.”

  When she started as a junior associate in Atlanta, the flexibility in her schedule she had previously enjoyed was gone. Napping did not seem like an openly acceptable option. This was the land of billable hours; there were partners and clients to satisfy. She started putting in seventy-hour weeks. Even if she did take a nap, she found it made her feel worse. “That’s when it finally hit me,” she said.5 “This is not how you’re supposed to feel.”

  Fast forward a decade. While preparing to write this book, I visited Anna at her law firm’s offices in Atlanta. We bought sandwiches for lunch and sat on benches outside. The book mostly won’t be about you, I told her cautiously. Although others had called her a “sleeping beauty,” Anna said the vision of her as a passive damsel in distress didn’t apply: “I think I’m actually an example of a patient advocating for herself, collaborating with her doctors, and not saying ‘OK’ when she’s told to just suck it up.”

  When the nursing professor Kathy Parker started discussing her case in public, Anna was uncomfortable. She didn’t want to be a poster child. She didn’t want her full name to be used or the name of her firm. But she became frustrated with the obscurity of idiopathic hypersomnia and the impasse in research, so a few years later, she agreed to participate in promoting the Emory team’s findings. As a result, she has received many phone calls from people with similar problems, asking for advice.

  After meeting other people with experiences like Anna’s, I wanted to learn more about IH’s back story and why it had been in the shadows for so long. IH was not a sudden epidemic but rather a slow undercurrent. Sleep medicine has flourished in the last few decades, but until recently, the boom has left out people with IH. Many in the field of sleep medicine considered the category of IH a hodgepodge: people made sleepy by a variety of factors, ranging from genetics to infections or head injuries. The problem was inherent in the name: idiopathic means “arising spontaneously or having no cause.”

  OVERDIAGNOSED OR OVERSHADOWED?

  The first person to identify IH as something coherent and distinct was Bedřich Roth, a neurologist at Charles University in Prague. In 1956, Roth published a paper on several patients with the symptom of “sleep drunkenness,” persisting long after they woke up.6 Here’s how Roth described an eighteen-year old training to be a locksmith, whose sister, mother, and aunt had similar conditions:

  He falls asleep on the tram, in the cinema, at a concert, in the doctor’s waiting room. The sleep sometimes takes only 10 or 15 minutes, but usually takes about 5–6 or even 16 hours. In the evening he falls into a deep sleep immediately. His family says it is almost impossible to wake him up in the morning; he often falls asleep again. Waking up takes about 15 minutes—the patient staggers as if he was drunk. Sometimes he even falls down. He is very rude and vulgar, unlike his normal behavior, and doesn’t perceive anything during this time.

  Acknowledged by his peers as a pioneer, Roth established one of the world’s first sleep labs in the 1950s.7 Resources were limited in Czechoslovakia, but he was able to collaborate with leading sleep researchers in Western Europe and North America. In the 1970s, Roth gave IH its name, proposing sleep drunkenness as one of its principal features.8 He died in 1989, just as Czechoslovakia’s communist government was fading away and the study of sleep disorders was transitioning from descriptive to molecular.

  Roth thought IH could be as prevalent as narcolepsy—usually estimated as around 1 in 2,000 people—or multiple sclerosis, now thought to appear in more than 1 in 1,000. Other sleep specialists did not adopt his perspective. IH was overshadowed as other disorders, such as narcolepsy and sleep apnea, became better defined. Current estimates of IH’s prevalence are several times lower (currently, around 1 in 10,000 in the United States), although the numbers are rising.

  After Roth, the French neurologist Michel Billiard is cited by Roth’s Prague-based colleagues as having done the most to refine the concept of IH as a separate sleep disorder.9 Billiard complained that the IH category was seen as a basket for every sleepy patient for whom an explanation was not available: “Idiopathic hypersomnia is frequently overdiagnosed due to a persistent tendency to label as such hypersomnias that do not fit the criteria of either sleep-disordered breathing or narcolepsy.”10 For IH, this tension between a coherent disorder and a leftover category has existed for years.

  RELATIONSHIP TO NARCOLEPSY

  Let’s lay out some basics. The details of where IH starts and other sleep disorders end may sound arcane to nonspecialists. Still, these distinctions have had tangible effects on patients’ lives, affecting how doctors, friends, and relatives view them.

  “Hypersomnia” broadly means “too much sleep”: chronically feeling sleepy during the day or needing excessive amounts of sleep. “Hypersomnolence” refers to the symptom rather than a disease. According to surveys, substantial fractions of the population of the United States experience excessive daytime sleepiness (about 5 percent) or the need for long sleep periods, enough to interfere with daily life (more than 1 percent).11

  Some people feel sleepy during the day because they experience insomnia at night. We are focusing on the opposite of insomnia: when sleep occurs readily but never seems like enough. A more difficult distinction to make is whether hypersomnolence comes from a psychiatric condition such as depression. IHers describe their excessive sleepiness as an external force that interferes with their ability to perform desired activities, rather than a companion of their mood.

  As currently implemented in sleep clinics, a crude definition of idiopathic hypersomnia is excessive daytime sleepiness, not sleep apnea, not narcolepsy, not lack of sleep, and not anything else. For someone to receive an IH diagnosis, common causes of daytime sleepiness such as obstructive sleep apnea or metabolic diseases should be eliminated. Hypersomnolent patients have shown up at sleep clinics and discovered to have vitamin D or B12 deficiencies.12

  Clinicians start with questionnaires such as the Epworth Sleepiness Scale, which asks how likely someone is to fall asleep during activities such as reading, watching television, or driving. Then they are supposed to have something “objective” to gauge a patient’s sleepiness. No biological test for IH exists, defining who’s in the club and who is not. Instead, extreme sleepiness is measured operationally: how quickly someone can doze off, given several opportunities during the day.

  Remember the five naps Anna was asked to take? They were part of the Multiple Sleep Latency Test, standard for diagnosing both narcolepsy and IH. Someone who goes to sleep quickly and enters REM sleep enough times (twice) has narcolepsy. Someone who goes to sleep quickly enough but does not enter REM sleep more than once has IH. Those who feel sleepy during the day but during the test don’t doze off fast enough are in limbo; their status depends on how much sleep they say they need and their physician’s judgment.

  In sleep medicine, it’s difficult to discuss IH without referring to narcolepsy, which has received more attention and has well-established patient-support organizations. This book highlights how people with IH felt their needs were not being met and created new organizations in response. That said, there is no need to create a competition between the two conditions. At the local level, groups that support and advocate for people with narcolepsy have included people with IH in their efforts for years. A woman who organized a support group for narcolepsy in Washington, DC, told me that people with IH started showing up because narcolepsy was the closest to their own diagnosis that they could find.13“There is so much overlap in symptoms that people with narcolepsy have always, in my experience, welcomed people with IH with open arms,” she said.

  The push for more recognition and awareness for narcolepsy has its pitfalls. Although television shows and movies have included fictional characters with narcolepsy, they are often portrayed for comic effect. One example: perennial bumbler Homer Simpson, diagnosed in a 2015 episode. A few celebrities, such as the late-night television host Jimmy Kimmel, have disclosed their narcolepsy diagnoses.14 Even so, surveys have found that fewer adults in the United States recognized the term “narcolepsy,” compared with other chronic diseases, and didn’t understand narcolepsy’s main features.15

  Most of the time when sleep scientists talk about narcolepsy, they mean narcolepsy with cataplexy, or narcolepsy type 1. Cataplexy is when someone experiences muscle weakness in response to strong emotions. Full-body cataplexy can make someone collapse, but it is often more subtle, involving only the face or part of the body. One of the most reliable triggers for cataplexy is laughter, complicating social life.

  In defining a disease, we can focus on the symptoms or the molecules. For narcolepsy type 1, the symptoms and the molecules implicated are well understood. For IH, as well as narcolepsy type 2, the symptoms are defined, but the molecules are not. Take a look at the current landscape in table 1.1. Several symptoms for narcolepsy type 1 tend to come together: excessive daytime sleepiness, disrupted nighttime sleep, cataplexy, sleep paralysis (waking up but then being unable to move), and vivid dreams that bleed into waking time, seeming like hallucinations. The last three have been thought to involve partial intrusions of REM sleep into the awake state.

  Narcolepsy type 2 is an in-between category, lacking cataplexy but having more of the other features of narcolepsy type 1. While having excessive daytime sleepiness, people with IH have fewer of the REM-related symptoms of narcolepsy. A distinguishing feature between IH and narcolepsy tends to be the effect of naps. People with narcolepsy type 1 often say a fifteen-minute nap makes them feel much better, but with IH, naps are generally long and not refreshing.

  Sleep drunkenness is a distinctive symptom of IH, although it is not present in all cases—Anna said she did not experience it. Sleep drunkenness, which can be independent of IH, has been defined as a period of confused clumsiness and slurred speech after waking up. It is sometimes thought of as a stronger, more extended version of sleep inertia, which most healthy people have experienced: a temporary groggy feeling upon waking. In sleep drunkenness, the transition out of sleep is incomplete, and the brain is stuck in a half-awake state. A related phenomenon is automatic behavior, or performing routine tasks like a zombie, which seems to occur as a result of extended time awake and pressure for sleep.