Suffering from insomnia? How about sleep apnea? Such easy questions to answer – or are they? We may attribute whether we feel good or bad upon waking up to the quality or duration of our sleep. But many people might not consider that their feeling might not quite match with what is actually going on during sleep. Mismatch, as the phenomenon is known, is more common than most patients – and even some doctors – may realize. What kinds of mismatch are possible?
The most concerning kind of mismatch is when a person feels that sleep is fine, and yet there is a potentially serious disease affecting sleep. How can that be? Many people don’t know that they have a breathing problem called obstructive sleep apnea, or OSA. In this disease, a person’s airway repeatedly closes down for 20-30 seconds at a time during sleep. These pauses in breathing interrupt sleep continuity, and the decreased airflow often causes the blood oxygen levels to drop. OSA is a well-known risk factor for heart disease, stroke and other medical problems.
As dramatic as this breathing problem may sound, we know from large clinical studies that about half of patients with obstructive sleep apnea are not sleepy during the day.
Sleep Apnea Denial?
As dramatic as this breathing problem may sound, we know from large clinical studies that about half of patients with obstructive sleep apnea are not sleepy during the day. That’s not simply because they are in denial or they drink coffee to compensate (although this certainly occurs in some cases). This surprising mismatch between symptoms and disease occurs even for patients who have severe obstructive sleep apnea, meaning that they stop breathing more than 30 times per hour – that’s over 240 times in an 8-hour night of sleep! Although we’ve got a lot to learn about why only some people become sleepy when their sleep is interrupted by OSA, the potential for mismatch between symptoms and OSA severity is one major reason diagnosis can be delayed.
The opposite kind of mismatch also occurs: some patients turn out to be sleeping much better than they think they are. This kind of mismatch is mainly seen in patients with insomnia. Although they may feel they are laying awake in bed, when tested in the laboratory their brain waves and other measurements indicate sleep is occurring.
Such a discovery can certainly come as a surprise for the patient. It seems so natural to know whether we are awake or asleep at night that some insomnia patients even question whether the sleep test data was mistakenly switched with another patient. Over the years, this kind of mismatch has gone by names such as misperception insomnia or paradoxical insomnia. We still don’t understand how or why this can happen. This is a critical area of ongoing research, because doctors depend on subjectively reported sleep patterns, such as a sleep diary, to diagnose insomnia and monitor treatment. How many of the tens of millions of insomnia patients requiring chronic medical care are experiencing misperception?
Insomnia and Misperception
What can we do about the fact that mismatch occurs in the two most common sleep problems? Awareness of the potential for mismatch is key for physicians and patients alike.
It seems so natural to know whether we are awake or asleep at night that some insomnia patients even question whether the sleep test data was mistakenly switched with another patient.
Doctors may use other clues, such as snoring or obesity, to direct them to test for sleep apnea. Yet patients may be unwilling to be screened if they feel fine. It may help to think of screening for sleep apnea like screening for high blood pressure or cholesterol, which generally do not cause symptoms.
Only some with insomnia will have an overnight sleep test in the laboratory, usually because their physician suspects another problem like sleep apnea. In fact, the general practice guidelines do not recommend that patients with insomnia undergo sleep testing in the lab. Insomnia may be a unique example of a medical problem whose diagnosis depends only on subjective symptoms when there is an objective test available. Some studies suggest that providing objective measurements of sleep to patients with misperception insomnia can actually improve the perception of sleep. This approach is an exciting area of research and may prove a useful alternative to sleeping medications, which carry significant risks.
To learn more about how you can support sleep research at Mass General, please contact us.
Insomnia and sleep apnea are key areas of research for Matt T. Bianchi, MD, PhD, director of Mass General’s Sleep Informatics Laboratory.