Common symptoms of Idiopathic Hypersomnia

Main symptoms

• Chronic excessive daytime sleepiness (EDS) which may manifest at any time. This makes it difficult to perform normal daily events, including both work and social activities. It is described as “never truly feeling awake”.  This is also described as a “loss of alertness”.
• Deep unfragmented sleep for more than 10 hours or more over a 24-hour period. Patients often report much more, though this may be less in older people.
• Long daytime napping, similar in form to the night time sleeps. This is an often an unplanned event. This might be throughout the day or episodic.
• Unrefreshing night and daytime sleep. The sufferer wakes up feeling as tired as when they went to bed. (This differs from Narcolepsy where naps are refreshing).
• A problem awakening even with loud alarms, or when being physically awoken.
• Sleep “drunkenness” upon waking. This is an inability to swiftly transition from sleep to wakefulness. This is a very severe form of “inertia” that many people experience on awakening; however, “sleep drunkenness” lasts a lot longer. Patients also report being short-tempered in this sleep drunkenness phase.
• “Brain fog” while awake; experiencing problems with memory, attention and concentration.

Other supporting symptoms

• Headaches on waking.
• Depression – this can be quite complex and the issue of mood disorders and hypersomnolence is poorly explored.
• Poor ability to adapt to relative extremes in temperature, something known as Thermo-regulation. These extremes, such as going out on a hot day, can cause the EDS to kick in.
• Raynaud’s disease which manifests as very cold hands and feet, often blue in appearance.
• Excessive sweating even in mild weather.
• Blood pressure dropping right after standing up (orthostatic hypotension).
• Sleep paralysis (being temporarily unable to move whilst waking or falling asleep).
• Sleep hallucinations (vivid dreaming that often feels like reality).

The route to diagnosis

So what is the process of determining if a patient in the UK has Idiopathic Hypersomnia?

As stated above, IH is a disease of exclusion. It should be diagnosed by a specialist with an interest in, and knowledge of, diseases of hypersomnolence. This may include sleep specialists but can include other neurologists, clinical psychiatrists and some pulmonologists.  In addition sleep physiologists and nurses are getting more involved and learning how to diagnosed the disorder.

However, there are some sleep specialists who are not confident with diagnosing IH at present, so don’t be put off.  If things are unsure, ask for a second opinion.

First steps to getting assessed

If you think you’ve got a problem sleeping too long or in the day, go and see your GP.  They will most likely want to check your iron levels, Vitamins B & D and your Thyroid function. They will also need to understand if you’re depressed.  If they do find something and treat it, your sleep should normalise.

However if nothing is found, or the sleep issue persists, ask your GP to refer you to a sleep centre. There are local and regional sleep centres around the country. The regional ones are generally more specialist, though there are very good non-regional Trusts.

The Sleep Apnoea Trust has a list of the sleep centres around the country.

Getting this referral might not be easy at first. However if your sleepiness persists, then they should refer you on. There is quite a long wait period to see a specialist, but getting on a list will get you seen sooner.

Don’t beat about the bush as I did and suffer needlessly; this is your NHS.

You may end up seeing a neurologist first, but they are a lead to the sleep specialists.

At the sleep centre

Once at a clinic the physiologists there will take a full case history, and get you to self assess on the Epworth Sleep Scale, to understand just how sleepy you are.

Don’t be concerned that this isn’t a doctor – the sleep physiologists are the real experts in the sleep centres, and sleep is their focus.

The sleep centres will possibly repeat the basic checks again. They will check for other illnesses and medications (prescription or personal) which can cause EDS, including such illnesses as sleep apnea, MS and Parkinson’s. These cause secondary hypersomnia. They will also want to understand if you’re sleepy or just fatigued.

Understanding the difference between sleepiness and fatigue

There is still  confusion between sleepiness and tiredness, which they will assess. With CFS/ME, patients often report suffering from excessive fatigue and tiredness and retire to bed to rest and maybe nap a little.

However, IH and Narcolepsy are diseases of sleepiness (with a side helping of fatigue). That differentiation is important to the diagnosis. People with IH go to bed to sleep on a regular basis, and it’s worth remembering that differentiator.

Other causes of Hypersomnia

The doctor will also want to understand if you’re self-medicating, or taking any non-prescription drugs, including recreational ones.  These may be the cause of some of your problems. If you end up having an over-night test, this will be checked through blood and urine tests.

They will also look to rule out depression as a cause; however mental health issues and sleep disorders seem to go hand in hand.  This is a big topic in its own right, and being addressed in the recent reclassification papers.

Also, Insomnia may cause EDS but as good quality night-time sleep is part of the diagnosis, regular insomnia will rule out a diagnosis of IH.  Insomnia can co-exist with Narcolepsy though, and is a useful differentiator.

Night-time sleeping

They will also need to be a check that you’re getting a full night-time’s sleep, and will most likely ask you to record a sleep diary to see how often you sleep in your opinion. Sometimes, 7 day actigraphy, will be used instead.

This sleep diary will be your record of both when you go to bed and arise and when you sleep and awake. It may include when you have stimulant drinks, and when you take other medication. It may ask for if/when you nap in the day, and for how long too.

Asessing for Sleep Apnea

The next check is normally to see if you’re suffering from one of the Sleep Apneas, which will stop you getting a good night sleep. This is often a major complaint around EDS. Sorting these issues out may lead to the EDS disappearing of its own accord, which is a positive solution.

If they find moderate or severe Sleep Apnea, they will most likely treat with a CPAP breathing device. If that treatment is adhered to, but the EDS persists, then the next step is a polysomnogram and MSLT.

Attending a sleep study

An overnight study usually is done in an NHS sleep centre; now home testing is available too as Long Covid has put increasing pressure on sleep centres.

Patients are normally expected to stop all medications which affects your sleep. However, this is patient specific and should be discussed between the doctor and the patient.

These studies can be quite stressful as you’re covered in wires and sensors.  If you suffer from anxiety, talk to the sleep centre before hand, so you go into the study as relaxed as possible.  Maybe take a comfortable pillow or other personal items to make the experience less demanding.

A combined overnight and daytime sleep study (PSG & MSLT) will look at how long, and how well you sleep in the night, and the quality of your sleep. Six hours night time sleep is expected from the patient to allow the physiologists to make an accurate diagnosis, and to proceed to the MSLT.  This is to rule out insufficient night time sleep as a cause of daytime sleepiness.

Possible features of your night-time sleep could be:

• Is your sleep efficient, or are there constant arousals (even if you dont notice them). The latter might point to Narcolepsy.
• Are there muscle movements in your legs both before or during sleep. The former is a sign of Restless Leg Syndrome (RLS); the latter of Periodic Limb Movement Disorder (PLMD).
  
• Are you getting the correct mix of sleep; if your’re a light sleeper and not getting enough useful sleep then you may have Insufficient Sleep Syndrome. This often leaves the person tired in the day.

There are other sleep disorders including Parasomnias and Circadian Rythmn disorders which can also seriously impact a person’s sleep and well being.

Daytime sleep testing

The MSLT (Multiple Sleep Latency Test) assesses how quickly someone falls asleep, and how quickly they enter REM sleep. 4 or 5 tests are done 2 hours apart throughout the day. You will normally be awakened 15 mins after you fall asleep; however if you do not fall asleep the test will end after 20 mins. The night-time PSG can also be used as the first sleep session of this test.

The test also looks at how quickly someone enters REM sleep ( which is primarily a test for Narcolepsy).  These are known as SOREMP – Sleep Onset REM Periods – which need to occur within 15 mins of falling asleep.  2 or more SOREMPs are a possible indication of Narcolepsy.  1 or none usually mean IH.

It does not assess a patient for any of the characteristics of IH including issues when awakening.

Also the MSLT doesn’t take into account if your hypersomnia is episodic in the day, which may occur with IH.

As such researchers are coming round to the fact that the MSLT may be a poor tool to diagnose IH.  Unfortunately, it is one of the few tools in use.

Sleep test results

Once all these tests are completed, and analyzed, and all other causes of EDS are ruled out, then a diagnosis of Idiopathic Hypersomnia is possible. This should take into account the clinical features too, especially the sleep drunkeness and issues awakening.

Idiopathic Hypersomnia is believed to be much rarer than Narcolepsy. It is suspected to affect between 1 in 11,000, and 1 in 100,000 depending upon the form. The figure of 1 in 25,000 is often used.

As such there might only be a maximum of around 2500 people with IH in the UK. Many are still undiagnosed or worse misdiagnosed, and there are no UK based patient registries.  This means the actual number is un-diagnosed.

The disease affects more women than men too in the ratio 1.8:1, though this reason is unknown.