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Perchance to Dream
A Hopkins sleep disorders specialist weighs in on insomnia and body clocks.

Chances are you're not getting enough sleep, says Charlene Gamaldo. And sunlight—or lack of it—plays a key role in sleep/wake rhythms.

It seems sleep isn’t as sweet as it used to be. As many as 70 million Americans cope with chronic sleep disorders or sleep-related problems. And the average length of sleep on work nights has dwindled to six hours and 40 minutes, according to the National Sleep Foundation.

Neurologist Charlene Gamaldo, assistant director of the Sleep Disorders Center, says the majority of her patients struggle with such conditions as sleep apnea, a disorder characterized by pauses in breathing while asleep, and restless leg syndrome, a neurological condition that causes unpleasant sensations in the legs. Seasonal changes, however, can also affect how well people sleep. Gamaldo recently talked to Dome about how much sleep we need, how the body clock works and what happens on November 2 when we “fall back” to Standard Time.

How much sleep should most people get?
The average adult needs about seven and a half to eight hours of sleep. But that’s measured on a bell curve. There are folks who need a heck of a lot more and people who can do pretty decently with four or five hours, although they are rare. There are a lot more people walking around on only five hours of sleep than those who can function at their best that way.

How does your body know when it’s time to go to sleep or wake up?
We have a special area in the brain that’s in charge of sleep/wake rhythms. It uses cues in our environment to help set our body clock. The most powerful cue is sunlight. There are special cells in our eyes whose specific job is to pick up sunlight and send that signal to the body rhythm clock within an hour or so of waking you up. Then, 13 to 16 hours later, your clock knows it’s time to start preparing for bed again.
Another cue is body temperature. Increasing your body temperature sends an alert signal that it’s time to get going. That’s why taking a hot shower in the morning to wake up works so well.

Every fall and spring, people complain about adjusting to time changes. Is it really so hard to adjust your schedule by an hour?
Falling back to Standard Time is usually less of a problem than springing forward to Daylight Savings. With Standard Time, the sun rises an hour earlier so that people have more of a natural alarm clock, although this may initially disrupt the sleep of “night owls” who like to go to bed late and sleep in. There are also other issues in the fall. Because the days are getting shorter, some people feel more sluggish because there are fewer hours of sunlight to act as an alerter or as a natural “happy pill.”

What do you recommend that people do?
On days when the sun is going down around 4 p.m., it helps to get your fill of sunlight at lunch. [That exposure will also help against your body’s natural post-lunch dip from 1 to 3 p.m.] If you work indoors, lunch may be your only chance to get sunlight after you drive to work.

How did you become a sleep researcher?
Partly from professional interest, partly from personal insight. When I was a medical student and resident, sleep was often seen as a luxury you could do without. It became apparent, however, that I couldn’t function well on a limited amount of sleep. Sleep was as integral to my performance as eating. If I get too little sleep, even for a few days in a row, I see a difference. It takes me longer to think of the right word or figure out what I’m going to say.

What is the biggest sleep complaint?
For the general public, it’s insomnia: difficulty initiating or maintaining sleep. However, insomnia is just a basket term that describes a symptom caused by a number of different things. For instance, the reason for sleep difficulties could include primary sleep disorders, such as sleep apnea, or other medical conditions, such as pain or depression. Occasional bouts of insomnia are normal, but you should contact a sleep specialist if you have lengthy or repeated bouts that hurt your job performance, ability to concentrate, mood or social relationships.

—Linell Smith



Johns Hopkins Medicine

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