Dear Dream Doctor,

Through my childhood and as a young adult I was a sleep walker. Now as an adult of 42 years I have matured into night terrors (I guess getting up and walking around takes too much exercise).

It is the same fantasy setting each time; dark cave with moss and water coming down the walls and spiders coming after me. What has me so concerned is that I can open my eyes and tell myself I am dreaming but the vision of spiders does not go away. My poor husband tries to rationalize with me and I become even more angry and determined.

We have learned that if we keep the bedroom illuminated these episodes do not occur. However, every time the room is completely dark they do. This can be a problem when we are away from home.

My question is: Why do my eyes still see the dream vision when my mind is telling me it’s not there? Help!!

—Leslie, Age 41, Married 21 years, Shelton, WA, USA

Hi Leslie—

According to traditional sleep surveys, you are one of those “very rare” adults (less than 2%) who frequently experiences night terrors. But if you read as much mail as I do about this curious subject, you might begin to think night terrors are a lot more common than is generally believed. (And you would definitely know you’re not alone!)

Night terrors actually exist on a spectrum of “confusional arousals” from sleep that, as you correctly identify, also includes sleepwalking and talking. The reason why these three behaviors are grouped together is because they all share a common genesis—they are partial arousals from deep, (surprise...) non-dreaming sleep!

During the course of a night’s sleep, we oscillate between deep, light, and dreaming sleep stages in roughly ninety minute cycles. But occasionally (and this is true much moreso with children ages 3-5 than with adults) we experience an arousal from deep sleep (we turn over in the bed, adjust our pillows) that is not accompanied by a corresponding shift in sleep stage. The end result is that we can be partially awake—yet deeply asleep—both at the same time.

When we awaken in such a state, it is easy to be confused, and also to panic and become frightened. Within the spectrum of confusional arousals, then, a mild arousal might be your bedpartner’s frequent mumblings from sleep each time (early in the night) he or she turns over. If you are awake and answer your partner back, you quickly will realize that the talk is nonsense. You will not get a logical (awake) response to any of your inquiries.

Sleep walking is a more active confusional arousal. The sleepwalker “awakens” (but is still deeply asleep) and apparently believes he or she has somewhere to go or something to do. A “mild” sleepwalker may only sit up in bed and look around the room with a blank or confused expression before returning to sleep. A “calm” sleepwalker will get out of bed and walk seemingly purposefully about the house. An “agitated” sleepwalker may want to quickly leave the room, and “get away from something.”

Your arousals from sleep are accompanied by visual hallucinations, which would appear to indicate an arousal from REM, or dreaming sleep. Over the years though, we have learned that visual imagery also occurs in deep sleep, although it is simpler (one pressing image—like in your report) than the type of imagery we know accompanies REM.

The reason why leaving a light on in your bedroom eliminates the terrors is twofold. The light actually helps you to physically arouse better (come to a full awakening) from deep sleep. The light also allows you to orient better to your true surroundings. That is, when you awaken momentarily from sleep when the light is on, you are able to assess your environment well enough to remain calm and return to sleep (roll over) without event. If the light is off, though, you may momentarily wonder where you are—which allows that scary old image of the spiders at the waterfall to leap into your mind. The reason it stays “stuck” there is because it is very difficult to awaken directly from deep sleep. Usually it takes 10-15 minutes.