Are Insomniacs Unreliable at Assessing Sleep?

You’ve heard it said before: insomniacs typically overestimate how long it takes to fall asleep and underestimate the amount of sleep we get. Time and again, sleep experts ask us to estimate our sleep time. Then they conduct overnight sleep studies with polysomnography (PSG) and find, on average, that we fall asleep faster and sleep longer than we think.

Are insomniacs just unreliable when it comes to estimating time? What else might account for this discrepancy? Should we be reassured that we’re probably sleeping more than we think?

Insomnia sufferers underestimate how long they sleepYou’ve heard it said before: insomniacs typically overestimate how long it takes to fall asleep and underestimate the amount of sleep we get. Time and again, sleep experts ask us to estimate our sleep time. Then they conduct overnight sleep studies with polysomnography (PSG) and find, on average, that we fall asleep faster and sleep longer than we think.

Are insomniacs just unreliable when it comes to estimating time? What else might account for this discrepancy? Should we be reassured that we’re probably sleeping more than we think?

Time Estimates in the Daytime

Normal sleepers are fairly accurate when it comes to assessing their sleep. Their estimates of sleep onset latency (the time it takes to fall asleep) and total sleep time are in sync with the results of PSG.

Overall normal sleepers are also quite accurate at estimating time during the day. They can reliably estimate various time intervals (5 seconds, 35 seconds, 19 minutes) and keep a steady beat in a finger tapping task.

So can insomnia sufferers. Research suggests that overall, we, too, are quite accurate at estimating time intervals and keeping a steady beat during the daytime. It’s not the perception of time per se that gets distorted in insomnia. Insomniacs’ unreliability in estimating the passage of time occurs only at the night.

“It Takes Me Over an Hour to Fall Asleep”

Most studies show that people with chronic insomnia tend to overestimate sleep onset latency. For example, after having a sleep study, you’re told you drifted off 25 minutes after closing your eyes but you could swear it took you at least twice as long to nod off. How to account for this discrepancy?

One thing to keep in mind is that Stage 1 sleep—the lightest sleep stage, when the faster, unsynchronized brain waves associated with wakefulness are slowing down into more synchronized alpha and theta rhythms—is easy to perceive as wakefulness. In fact, if you’re woken up during Stage 1 sleep, you may feel you were never sleeping at all.

Research has also shown that unlike good sleepers, insomniacs tend to have elevated levels of high-frequency brain activity in the period leading up to sleep. These faster brain waves are associated with pre-sleep cognitive arousal—with thinking, rumination, and worry. They’re also associated with low-level awareness of what’s going on in the environment—a flushing toilet, a flash of lightening, the smell of skunk wafting through the window.

Unsurprisingly, insomniacs have been shown to take twice as long as normal sleepers to descend into deep sleep. So we’re hovering longer in the lighter sleep stages. All these things could help explain why we perceive we’re taking longer to fall asleep than PSG says we are.

“I Don’t Get Much Sleep”

Not all insomniacs are created equal. When it comes to estimating total sleep time, some insomnia sufferers are relatively good at it. (And results of some studies suggest that some insomniacs actually overestimate their total sleep time.) These are the so-called objective insomniacs, whose estimates of sleep time match up pretty well with their assessments by PSG. The diagnosis for this type of insomnia is often psychophysiological insomnia.

People whose sleep studies indicate they’re consistently sleeping less than 5 hours a night are called “short sleepers.” Short sleep is associated with physiological hyperarousal and an elevated risk for related medical disorders, as well as persistent trouble sleeping. Of all the variants of insomnia, short sleep is thought to be the most severe.

All I Get Is 1 or 2 Hours”

Other insomniacs’ perceptions of sleep duration are wildly at odds with assessment by PSG. A person who complains of getting just 1 or 2 hours’ sleep a night and goes in for a sleep study is often found to be sleeping 6, 7, or even 8 hours a night. The diagnosis in this situation is paradoxical insomnia, a disorder affecting about 26 percent of people with chronic insomnia.

Because their sleep duration is normal and their sleep architecture (as assessed by PSG) largely intact, the thinking is that these insomniacs are getting most of the benefits that sound, sufficient sleep affords. This may be reassuring. But the jury’s still out on the underlying mechanisms at play. Multiple irregularities may contribute to the feeling of being awake when most of the brain is asleep.

The Upshot

Should we be relieved to know that most of us are getting at least a little more sleep than we think? It’s not a bad idea. Once I stopped caring about how much I was sleeping, my sleep improved. Whether or not this would be borne out in a sleep study, it feels like I fall asleep faster and sleep longer than I did before.

If you can swallow the idea that in this one place your perceptions might be a tad unreliable (believe me, I know how hard this can be!), you won’t regret it.

Psychophysiologic Insomnia: What It Is & How to Cope

Psychophysiologic insomnia: This was my diagnosis when I finally decided to see a doctor about my sleep. I didn’t like the sound of it. “Psycho” came before “physiologic,” and to me the implication was that my trouble sleeping was mostly in my head.

My insomnia felt physical, accompanied as it was by bodily warmth, muscle tension, and a jittery feeling inside. I was anxious about sleep, too, and my thoughts weren’t exactly upbeat. But surely putting the psycho before the physiologic was putting the cart before the horse?

Psychophysiologic insomnia is a sleep problem involving physical and mental factorsPsychophysiologic insomnia: This was my diagnosis when I finally decided to see a doctor about my sleep. I didn’t like the sound of it. “Psycho” came before “physiologic,” and to me the implication was that my trouble sleeping was mostly in my head.

My insomnia felt physical, accompanied by bodily warmth, muscle tension, and a jittery feeling inside. I was anxious about sleep, too, and my thoughts weren’t exactly upbeat. But surely putting the psycho before the physiologic was putting the cart before the horse?

Don’t let the terminology put you off the way I did. Psychophysiologic insomnia (I’ll call it PPI) is a problem in which constitutional vulnerabilities, situational factors, habits, and dysfunctional thinking are so intertwined that it’s hard to sort them out. Here’s a brief description and recommendations on how to manage it.

A Diagnosis Based on Symptoms

No objective test can reliably distinguish between normal sleepers and people with PPI. So the diagnosis is made based on symptoms alone. In PPI as in other types of insomnia, the wakefulness may occur at the beginning, in the middle, or at the end of the night. But people with PPI also:

  • have a lot of anxiety about sleep
  • are prone to intrusive thoughts and involuntary rumination
  • feel physically wound up
  • fall asleep at unusual times and places
  • experience daytime impairments such as fatigue, moodiness, and trouble thinking

Polysomnography (PSG)—the test administered overnight in a sleep lab—is not usually recommended because it doesn’t discriminate well between people with PPI and normal sleepers. But PSG results show that overall, people with PPI sleep less, and spend more time in lighter stages of sleep, than people who sleep well. (In contrast, the PSG results of people with paradoxical insomnia look normal, even though sufferers may feel like they’re getting 1 or 2 hours of sleep at best.)

How PPI Develops

Often it begins in adolescence or early adulthood, showing up as light sleep or periodic episodes of poor sleep.* Some people are naturally more susceptible than others. This may be true, sleep expert Peter Hauri has written, because of “an inherent, mild defect in the sleep-wake system, i.e., either excessive strength of the reticular activating system [the arousal system] or a weakness in the inhibitory, sleep-inducing circuits. Because the sleep-wake balance in such patients might lean toward wakefulness, such people would be suffering from an occasional, neurologically based poor night of sleep long before developing serious insomnia.”

Stressful situations lead to more extended bouts of poor sleep. Sooner or later, concern about sleep sets in. This is when insomnia starts to get “serious,” to use Hauri’s word. Looking for ways to reestablish better sleep, people change their habits—trying harder to sleep, going to bed early, taking naps—in ways that actually make sleep worse. The bed and the bedroom come to be associated with not sleep but rather with wakefulness and worry about sleep.

Thus begins the vicious cycle where long stretches of wakefulness in bed, accompanied by feelings of tension, begin to condition arousal of the brain, in turn fueling more bodily arousal. What began as light sleep or an occasional stress-related bout of insomnia has become a chronic affair.

Management Options

Once the PPI train pulls away from the station, it’s hard to get off. For decades I tried every trick in the book—sleeping on the couch, watching nature programs, listening to white noise, scenting my pillows, rhythmic breathing, drinking tea made from Chinese herbs. Nothing worked for long or without cost.

The good news is that PPI, unlike some other types of insomnia, responds well to treatment with cognitive behavioral therapy for insomnia (CBT-I). (While the name might suggest that it’s similar to conventional talk therapy, CBT-I is mainly focused on helping people modify habits.) For me, sleep restriction therapy, a treatment offered as part of CBT-I, was especially useful. Sleep restriction led to an awareness that my sleep could be reliable if I timed it right.

Equally important, though, for people whose insomnia feels physical (like mine) is finding a way to tamp the physiological arousal down. What works best for me is daily aerobic exercise. Research also suggests that mind-body therapies such as yoga, tai chi, and mindfulness meditation are helpful in this regard.

If this sounds like the type of insomnia you’ve got, check into CBT-I and physical training. There’s nothing to lose and much to gain.

How do you manage your insomnia? Has your strategy worked?

* Lee-Chiong T. Sleep Medicine: Essentials and Review. New York: Oxford University Press; 2008: 84.

Sleep Studies: Do You Really Need One?

If you haven’t had a sleep study, you may wonder if spending the night at a sleep clinic might help the doctor understand your problem and how to fix it. Polysomnography, or PSG, is the test conducted at the clinic. New guidelines from the American Board of Internal Medicine (ABIM) clarify when PSG is useful in cases of chronic insomnia and when it isn’t. Here’s a summary and explanation of the guidelines.

Sleep studies are useful when insomnia is complicated by another disorderWhen I ask people with persistent insomnia if they’ve had a sleep study, the common responses I get are these:

  • “I had one and all I learned from it was that I don’t have sleep apnea.”
  • “I want one, but my doctor won’t write the prescription.”

If you haven’t had a sleep study, you may wonder if spending the night at a sleep clinic might help the doctor understand your problem and how to fix it. Polysomnography, or PSG, is the test conducted at the clinic. New guidelines from the American Board of Internal Medicine (ABIM) clarify when PSG is useful in cases of chronic insomnia and when it isn’t. Here’s a summary and explanation of the guidelines.

When a Sleep Study Is in Order

PSG is good at detecting sleep apnea, sleep-related movement disorders, and violent or harmful behavior that might be occurring at night. If a doctor suspects that your insomnia is associated with any of these disorders, you’ll likely be going in for a sleep study.

Occasionally a person with insomnia reports such an unusual assortment of symptoms that, even after taking an extensive patient history, the doctor can’t figure out what’s going on. Here, too, PSG may help. The doctor may also prescribe a sleep study if you’ve undergone treatment for insomnia (with or without drugs) but your sleep has failed to improve.

When Sleep Studies Won’t Help

But neither the ABIM nor the American Academy of Sleep Medicine recommends sleep studies for other insomnia patients. Here are some of the reasons.

1.  PSG cannot do much except confirm the symptoms you report to the doctor during a clinical interview.

  • Let’s say you wake up several times at night and have trouble falling back to sleep. PSG may confirm that you experience these wake-ups but will not shed light on why.
  • Or maybe your problem is that it usually takes you a long time to fall asleep. Upwards of $2,000 is a lot to spend on a procedure that merely corroborates what you already know.

2.  PSG does a poor job of discriminating between normal sleepers and people with insomnia. In fact, up to 50 percent of the time, the brain activity of insomniacs looks identical to that of normal sleepers.

3.  In some insomniacs, there is abnormal brain activity occurring at night—activity typically associated with being awake. But standard PSG will not show evidence of this wake-like activity. As a measure of what’s going on in the brain at night, PSG is not finely tuned.

4.  Finally and importantly, in most cases of persistent insomnia, PSG will not suggest a course of treatment that differs from treatment that would be prescribed based on a thorough clinical interview.

  • If your complaint is that you’re a light sleeper and wake up frequently at night, the doctor will probably prescribe cognitive-behavioral therapy for insomnia (CBT-I) or some other behavioral treatment before considering medication. PSG might corroborate your symptoms but would not alter the diagnosis or the treatment.
  • Or let’s say your main complaint is that your thoughts keep you too wound up at night to fall asleep easily. The doctor isn’t going to need for you to undergo a sleep study in order to diagnose and treat the problem.

The Bottom Line

Sleep studies are an indispensable tool for people suspected of having sleep apnea and many other sleep disorders. But as conducted now, they’re of no help to insomnia sufferers unless your insomnia is related to another health problem.

If you’ve had a sleep study, what did you learn from it?