Category Archives: Sleep

At the Gates of Sleep

November 18, 2012 By in Brains, Kids, Sleep Tags: , , , , Leave a comment

497736998_45c09a136e_oNow that my daughter is about to reach her first birthday, I’m in the mood to reflect on the year that just passed. Unfortunately, my recollections of it are a little fuzzy, probably because I can count on one hand the number of times I’ve enjoyed a good night’s sleep over the past year. Some people have babies who regularly sleep through the night and I am happy for them. Truly, I am. But clearly I was not meant to be in their ranks.

Still, the never-ending parade of nighttime awakenings has taught me something about my own brain. It is precisely tuned to hear my baby. Although I sleep blithely through my husband’s thunderous snoring and the loud buzz of his alarm clock – multiple times a day, thanks to the snooze button – I awaken at the faintest sound of my daughter’s sighs, coos, or grumbles. When she cries, I am immediately awake while my husband sleeps on beside me, undisturbed.

People are generally able to sleep through minor sounds and sensations thanks to a subcortical structure in the brain called the thalamus. This structure receives incoming signals from our senses and relays them to cortical areas devoted to processing sensory information like sounds or tactile sensations. When we’re awake, the thalamus faithfully relays nearly every sensory signal on to the cortex. But when we’re asleep, neurons in the thalamus participate in strong, synchronized waves of activity that squelch incoming signals. As a result, about 70% of these signals never make it to the cortex. This process, known as sensory-gating, is how we manage to sleep through the roar of rainstorms or the brush of the sheets against our skin each time we turn in bed. It is also how we sleep through our husband’s room-rattling snores.

Yet some sensory information does get through to the rest of the brain during sleep. These signals do get processed and can even wake us up if they are either intense (like a loud noise) or personally relevant. A clever study illustrated the importance of personal relevance by exposing sleeping subjects to a loud presentation (via tape recorder) of their own name spoken aloud. The scientists played the recording either normally or backwards and found that subjects awoke in less than half the time when they heard their names presented in the recognizable form.

So did my daughter, in effect, sleep train me by training my brain to recognize her sounds as personally relevant? It’s a plausible explanation, but one that is ultimately lacking. It cannot explain that first night when I slept beside my baby at the hospital nearly one year ago. Although I had labored through the entire night before and had not slept in the ensuing day, I awoke constantly to every little sound my mewing newborn made, not to mention the cries that told me she wanted to nurse. She’d had no time to train me; I had come pre-trained. Just as my breasts were primed to make milk for her, my brain was primed to wake for her. We seemed to be engineered for one other, mother and child, body and brain. And we spent that first long night discovering how clever a designer Nature can be, while my husband slept peacefully on the couch.

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Photo credit: planetchopstick

On Nano-Naps and Dreamscapes

April 8, 2012 By in Kids, Sleep Tags: , , , , Leave a comment

New mothers must be collectors of broken sleep, eagerly taking a sliver here, a shard there – whatever they can get.

Now that my baby is four months old, she’s finally sleeping at night. Still, she wakes me every two hours to nurse. She is half asleep while she feeds and I am always nodding off. In the few seconds it takes for my sinking head or my nursing baby to summon me back, I’ll have a momentary dream. A micro-dream. A nano-nap. No more intricate dreams of forgetting to do my homework or going to prom in a maternity dress. These dreams are all business: snapshots of everyday life. Once it may be a view of my husband lifting the baby out of her crib. Another time, I glimpse a lump in bed beside me and realize it’s my baby buried in our blankets (a terrifying dream.) But usually I simply dream that she’s nursing. A dream of mere reality: no more, no less.

How do I even know that I’m dreaming? The details are off. And in these cases, the switch from dreaming to wakefulness can be particularly strange. Once the transition felt as seamless as a change of camera shots in a television show. One moment I was looking down at my nursing baby; the next, she was flipped (mirror-reversed) in my arms and her head was noticeably smaller! Never before have I had such an immediate comparison between the mind’s eye and the naked eye, nor realized how very similar they feel. And never before have I had such uninventive, literal dreams. It’s as if I can’t muster the energy to dream up anything better.

In the face of my lackluster dreaming, I am all the more fascinated by the rich dream life of my daughter. From the day she was born I’ve watched her smile, pout, and wince and heard her scream and giggle madly in her sleep. In fact, she smiled in her sleep months before she gave us her first waking smile. Physicians have observed rapid eye movements in fetuses, suggesting that babies dream in the womb. But what are they dreaming of? Is it limited to what they know: heartbeats and jostling and amniotic fluid? Or perhaps their dreams are wilder than our own, unconstrained by the realities of life on this earth. After all, the infant brain contains legions of unpruned synapses and far more neurons than that of an adult. Who’s to say what sort of fantasy it might come up with?

Whatever sort of dreams a newborn has, we don’t remember them as adults. By late infancy, we’ve already pruned enough synapses and experienced enough of the world to have a basic vocabulary for our dreams. An adult’s dream may create some odd combinations – eyeballs growing on trees or hats that unfurl into snakes – but the vocabulary, the unitary elements, are fixed. Eyeballs, trees, hats, snakes. Grow, unfurl. Our potential dreamscapes are wholly constrained by the details of our waking existence.

As my baby examines new places and things, I am reminded that she’s cobbling together her own vocabulary of the world. She will store away sensations, objects, creatures, actions, concepts, cultures, and myths. A knowledge that the sun shines from above and plants sprout from below. That rivers run and lakes loiter. That caterpillars turn into butterflies and never the other way around. For better or for worse, her future dreams will be shaped by the idiosyncrasies of our funny little world.

Dreaming of Me

October 10, 2011 By in Pregnancy, Sleep Tags: , , 5 Comments

My belly button has all but disappeared. In its place, an odd little pillow of skin lies flush with the rest of my stomach. A dark line – the linea nigra – now runs down the length of my abdomen, dividing me in two. My appendix and intestines, previously at home in my abdominal cavity, have been pushed up and to the sides so that they now form mysterious bulges just below my ribs. Stranger still, I find myself in possession of someone else’s breasts. And then there’s the most noticeable change: the beach ball sized stomach that wholly eclipses my view of my feet.

Of course these changes didn’t come on all at once. I’ve had many months to notice and adjust to them. Still, they’ve happened more rapidly than any other physical changes I’ve experienced in my life. Faster than an adolescent growth spurt, certainly, or any weight gain or loss. My brain has had trouble keeping up. I bump into things with my belly, forgetting its size. I struggle to maintain my balance as my vestibular system tries to adjust to my changing weight distribution. But the lag that has fascinated me most is how I envision myself in my dreams.

Even months into my pregnancy, after my stomach had visibly ballooned, the self I inhabited while dreaming remained as lean as ever. Although thoughts of my pregnancy filled my waking hours, at night I wasn’t the least bit pregnant. In fact, I often dreamt of myself as a high schooler again, wandering the halls without a class schedule or scrambling to find a bus that would deliver me there on time. Why high school? I don’t put much stock in the elaborate interpretation of dream symbols, but I imagine that my dreams of being a lost high school student reflect my waking awareness that parenthood is at my doorstep and I am unprepared. In the face of such a dramatic life change, I can’t help but feel that I’ve lost my lunchbox or forgotten a homework assignment somewhere.

Then, a month or so ago, my dreams began to change. Or rather my dream self changed. My new self often had a swollen midsection and wore maternity clothes (or in one case, a maternity prom dress). She couldn’t drink alcohol and got worn out just walking from the car. The dreams weren’t usually about my pregnancy; my enormous belly was simply present, just like my arm, hands, and feet. Something about my self-image, my internal body schema, had updated. A switch had been flipped and my mind was caught up with my changing body.

I began to wonder about these internal self-schemas that reveal themselves in our dreams. Do other pregnant women experience the same switch and a similar lag? And how long does it take for them to switch back after they’ve delivered their babies? What about other changes to one’s appearance, like growing or shaving off a beard? Or, in a more dramatic example, what happens when someone loses a limb?

I haven’t found much written on baby bumps and beards, but several people have studied whether amputees dream of themselves with intact or amputated bodies. The answer, in short, is it depends. One study found that a majority of surveyed amputees dreamt of themselves with amputated bodies at least some of the time. Among them, 77% made the switch within the first 6 months following their amputations. But the study also showed that a surprising percentage of the surveyed amputees (31%) dreamt exclusively of themselves with intact bodies, even a decade or more after their amputations. Preliminary findings suggest that those who undergo the amputation at a later age, those who regularly use a prosthetic limb, and those who experience phantom sensations from the missing limb may all be more likely to dream with their bodies intact.

It should come as no surprise that the results of the studies are complicated and variable. We can’t expect anything as complex as dreams and internal self-representations to be wholly consistent from person to person or from one dream to another. In my case, I may be pregnant in one dream but not in the next. At times I even dream I’m someone other than myself. Wading into dreams can be a messy business, certainly, but my curiosity is piqued and I’m eager for more data. To all those pregnant or post-pregnant ladies, beard growers, or head shavers out there: please comment and share your experiences! How long did it take for your dream self to catch up with the real thing?

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Photo credit: Sabin Dang

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