Idiopathic hypersomnia: feeling tired all the time

Life in the 21st century proceeds at a chaotic pace, leaving so many of us feeling like we are exhausted all the time.

To be sure, the fatigue is real: we're working overtime, not sleeping enough, and hauling around a sizable amount of sleep debt as a result.

But there's a small fragment of the population who suffers from a sleep disorder that leaves them feeling tired the moment they wake up from 10 hours of good sleep.

They are easily defeated by the irresistible siren song of daytime sleepiness in the middle of the work day. They never feel awake, no matter how much caffeine they consume. 

What's more, these people—who suffer from a condition called idiopathic hypersomnia—are challenged to find solutions to this life-altering condition. 

What is Idiopathic Hypersomnia?

Idiopathic means "without explanation" or "mysterious." Hypersomnia means "excessive sleepiness." Idiopathic hypersomnia, or IH, is medically classified as a central disorder of hypersomnia.

There are two kinds of IH: Primary IH and Secondary IH. 

Primary IH is diagnosed only after no known cause for chronic excessive daytime sleepiness can be identified.

Secondary IH occurs as a symptom of another medical condition. These include dysfunctional problems with nearly every system in the body, as well as sleep disorders. Once the root cause of these health problems is identified and treated, the symptom of hypersomnolence usually goes away and the IH diagnosis is discounted.

There is a further distinction made between IH with long sleep time versus IH without long sleep time:

IH with long sleep time means sufferers sleep more than 10 hours a night, while

IH without long sleep time means sufferers sleep less than 10 hours a night

What is the difference between narcolepsy and idiopathic hypersomnia?

The symptom of cataplexy is a key marker for distinguishing narcolepsy type I from IH. However, those who have narcolepsy without cataplexy must also be tested to differentiate them from those with IH.

Type II narcoleptics experience two or more sleep-onset REM periods on an MSLT (multiple sleep latency test),whereas those with IH do not. People with IH are typically more quick to fall asleep than normal sleepers, but not as quickly as their narcoleptic cousins.

The MSLT is currently the only way to distinguish one from the other, but results aren't always conclusive. People with IH have symptoms that very closely mimic type II narcolepsy, and vice versa. Because of the nature of the MSLT testing metrics, criteria to match either diagnosis can be met with an abnormal result. 

Sometimes people with IH will have several episodes of non-REM sleep—especially stage 3—that can last for up to two hours. This may help to differentiate them from narcoleptics, who experience quick trajectories into REM sleep for much of the night.

People with IH may also awaken the next morning in a stage of altered consciousness called "sleep drunkenness" lasting up to 4 hours. On the other hand, a person with narcolepsy will awaken refreshed.

Idiopathic hypersomnia symptoms

Aside from excessive daytime sleepiness, these symptoms also correspond with IH:

Idiopathic hypersomnia theories

There are a few theories about what causes IH.

"Garden variety" hypersomnia

Hypersomnia isn't always idiopathic. Here are some potential explanations for why you might be feeling so tired all the time. Examining these can help your sleep physician "rule in" or "rule out" IH and point to other solutions you can seek to reclaim your energy.

Opioid use

We often take medications for one health problem without realizing they can lead to side effects that make us feel like we have another health problem. Such can be the case for the widespread use of opioid pain medications.

Though the labels indicate that these drugs "may cause drowsiness," we forget they are linked to these side effects if we take these meds over a long period of time. Often, a change in medications, dosage, or frequency can help offer relief.

Hidden or undiagnosed medical problems

Sometimes a person with hypersomnia has not yet identified a measurable root for their excessive sleepiness. People with certain kinds of neurological disorders, like lupus or multiple sclerosis, may not experience other outward symptoms of their disorders and only have chronic hypersomnia to claim as a symptom.

If they later discover they have such a condition, then technically they can't have a diagnosis of IH since a measurable biological explanation for their extreme fatigue has been identified. Hypothyroidism, mental health diagnoses, and celiac disease are other health concerns that may also present with hypersomnia as a symptom. 

Mental health concerns such as depression and anxiety may also be the root cause behind periods of hypersomnolence.

Post-traumatic hypersomnia

A traumatic brain injury (TBI) can lead to central nervous system problems that linger long after the injury seems to have healed. Excessive daytime somnolence, cognitive dysfunction, lack of motivation, and feeling "out of gas," are side effects related to TBI as well. 

Insufficient sleep

For whatever reason, a person who is not getting enough quality sleep at night is bound to experience hypersomnia. Reviewing sleep patterns, habits, and schedules should help decide whether sleep deprivation caused by irregular bedtimes, shift work, or other self-imposed limits on sleep might be to blame for excessive daytime sleepiness.

Other sleep disorders: residual effects after treatment

Sometimes the "leftovers" from an adequately treated preexisting sleep disorder can still cause unwanted hypersomnia.

A person with obstructive sleep apnea (OSA) may be compliant with their continuous positive airway pressure (CPAP) and still have residual excessive daytime sleepiness.

Someone with narcolepsy who takes an alertness medication may still experience residual problems with cognitive function as well. 

A word about sleep state misperception: Many people with insomnia, when studied in a clinical environment, discover they sleep far more than they actually believe. This is called "sleep state misperception," and it's a fairly common occurrence.

For hypersomniacs, sleep state misperception can also occur: they might think they are actually sleepier than they are, which may be based on a long-standing problem with sleep debt (the outcome of sleep deprivation), which they have not been able to reconcile. It could also be something as simple as aging, which has a normal impact on sleep efficiency and quality over time.

Idiopathic hypersomnia treatment

IH forces people out of jobs or makes work life a living hell. The disruption that IH brings to these people's lives is devastating enough, made even more challenging in a culture where invisible illness, however disabling, is still viewed as laziness.

If you feel your life has been significantly altered by your daytime somnolence and you have had symptoms for at least 3 months, you may wish to speak to your doctor about a potential IH diagnosis. 

A differential diagnosis is required to narrow down root causes for IH. For a differential diagnosis to take place:

A diagnosis of IH can only happen after extensive testing takes place. If, after investigating all these possibilities, your physician diagnoses you with IH, you have a handful of treatment options. The following medications are, or could become, treatment options for people who have IH.

Stimulants: These remain the most common source of relief for those with IH. Stimulant drugs used to treat excessive daytime sleepiness include modafinil, ADHD medications, antidepressants, amphetamine-like compounds, and sedatives. Amphetamine-like stimulants are typically monitored to guard against tolerance and dependence.  

Flumazenil: This medication, based on a specific "somnogen" unique to the spinal fluid, is currently in phase 3 clinical trials and has been shown promise as a potential IH treatment. It essentially reverses the influence of an unidentified "somnogen" which over-enhances one's natural GABA, the brain's key sleep-regulating substance.

Clarithromycin: This common antibiotic has been shown to decrease daytime sleepiness in people with IH that could be related to GABA regulating processes. 

Current pharmacological treatments may offer welcome relief, but sometimes they can only be partially helpful. Other treatment approaches include cognitive behavior therapy in some cases. Aggressive treatment of other sleep disorders or other medical conditions can relieve the symptoms of IH, as these can still leave behind that constant "foggy" feeling throughout the day even with therapy.

Even partial treatment is a blessing for many; it allows them to drive safely, keep working at jobs they love, and make the most of the time they do have when they are feeling most awake and alert.  

Lifestyle choices that can help reduce sleepiness include the avoidance of alcohol or other drugs that can make you sleep, working only during the day, and keeping to a normal, regular bedtime schedule.

Ultimately, research is still needed to solve the complex puzzle that is idiopathic hypersomnia, to conclusively identify root cause, improve accuracy of diagnosis, and bring more and better treatment options for those who suffer from it.


Emory University
Hypersomnia Foundation
International Classification of Sleep Disorders (3rd Ed.)
The Promise of Sleep. W Dement, ©1999
Sleep Review
Stanford Health Care
US National Library of Medicine/Medline

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