"Insomnia is a worrisome concept marketed into a big business. There isn't 30 minutes' worth of difference between an insomniac and a non insomniac," a research physician dealing in sleep studies and mental health told me recently.

Most doctors agree that only 1 percent of the American people suffer from persistent insomnia. But the aura of insomnia is so blown out of proportion by effective drug-industry advertising that, during the course of a year, about 5 to 10 percent of the population spends around $26 million on hypnotic agents-barbituates and sleeping pills. Certainly Washington ought to qualify as town of would-be insomniacs. I decided to find out for myself and, a few Saturdays ago, began my all-night search. SATURDAY, 11:30 p.m. Drive to 19th and M NW to join the roller skating action. Reach 19th Street, but traffic is stopped at N. Spot four skaters lingering, breathing heavily on a corner. I pull over, hop out, call at them. They are Joe L. Mitchell, maintenance worker, D.C. Public Schools; Michael Thompson, printer; Cecilia Davis, secretary, Department of Recreation; and Judy Wilson, no available occupation for publication.

I look down at their high-stepping, above-the-ankle, one-piece leather skates with wide blue plastic wheels and orange stoppers up front and ask, "What's up?" They tell me. The skates rent for $2.50 an hour. They do this every weekend. "Why?" I ask, "It makes us sweat," . . . "It's something different." "It eases your mind." . . . "It's the in thing," I ask, "Is it fun?" "Yeah, ya meet plenty girls." ; . . "It's fun to watch everybody fall." . . . "It makes me hungry." . . . "It beats sleeping." They turn the tables on me, ask, "What do you think?" "Well," " observe, "you've got 8 on the floor and sweat on your head . . . do you ever drink and skate?" "No time to do everything at once," I'm told. "By the way," I query, "any of you fall tonight?" Three of them nod yes, one replies, "On my knees and my ankles." I say goodbye and ankle it, heel-and-toeing down to M Street.

Several skate vendors are at their stands - Heaven Skates, Bazaar Roller Skates and five more. Speak to a proprietor. He works for Giant Food by day, hawks skate rentals by night. "Until 1 a.m.," he says, "the police shut us down then." "Where do people skate?" I ask. "On the sidewalk," he says. "It's not legal on the streets." "Tell me about it," I ask, and he does.

"It came from California to Washington in July. About a hundred people a day during the week and 300 on weekends. The tourists skate to Virginia, the White House, the monuments. The drinkers start at midnight, with the bar closings. They're a different kind of breed. They want to stay up all night. They don't want to go to sleep on the weekends. They want action." I cross the four corners. It's all the same. Everyone's skating in circles. Big circles, medium circles, small circles. I ask one of them "Why?" He replies, on the run, "Peer pressure, man, night life's got its peer pressure." I head for Georgetown. SUNDAY, 12:20 a.m. Park. Walk west on M Street. Four strollers deliberately bump into me at once. I grab my wallet, feel reaching fingernails jamming my rear pocket, trying to pass my guarding palm. They fail. The four pass into the crowds as quickly as they came, emptyhanded. Reach Gunchers, note plaque, "Gunchers: The overzealous pinball player constantly tilting, gunching, jarring the machine known to other devotees as a Guncher." I pass the fun-house mirror in the bricked lobby, see James Evans, doorman and bouncer. "You ever throw anybody out?" "Only once," he replies. "Six guys tried to beat paying their check. I caught them . . . The cops helped;" He smiles.

I head into the music-filled room -- Jackson Brown songs -- past the eaters, drinkers and penny-arcade games. Fortune Gaze, Future Family Partner, Strength Tester, Weight Scale, Booze Barometer, metal stamper and gum-ball machines. Am now in crowded pinball area.Head On-Computer, "a multi-phase game," is popular. Gamesters driving against computer car, trying to clear all lane markers without crashing. Gunchers playing Pinball Pool, howling for a 300,000 score for one free credit. Others plunging at The Phoenix. More people at Starship One, shooting down computer missiles on screen with video torpedoes and firing at spacecraft with lasers. The players attack, the machine dials in, "You are now in command." The players in the room are competitive, excited, serious. Some are high. The room is hot and steamy.

In the dining area Blondie's voice is belting out "Heart of Glass." I order a small chsses pizza and draft beer. Not great but not bad. Service is good. Ask the manager, Brian Maloney, "When does it all end?" "We close at 3; our own cocktail hour starts at 4, after we clean up. Usually at a friend's apartment. It takes us a few hours to wind down. It's like choir practice. We're night people. We serve the day people at play. On weekends they'd love to play all night."

I slot a coin into a fortune-teller machine and get a card. "Your future life will be very sunny," the card prophesies. It's after 1 a.m. and getting darker. Next stop, NBC-TV and WRC radio studios on Nebraska Avenue. 1:20 a.m. In Master Control C Studio, NBC-TV station. "The football game ran late," Val Young, director, tells me. "Ran till 12:15. We're usually off the air by 2:30 or 3. But tonight, or this morning, we've got to push the usual late-night four hours of broadcasting till 4:15," she says, working with three assistants, Maurice Benjoar on slides, Yale Lewis on audio and Michael Swann at the buttons. Val calls the signals at the carts and tapes. "It's one-minute national commercial then one-minute local. That's the rhythm," she says. "People out there are watching and listening. Maybe just staring. Whatever, it's entertainment and they want to be entertained." I segue past half a dozen TV monitors to WRC radio, where bearded and bifocaled Peter Boyles is the midnight-to-5 talk-show host. 1:50 a.m. Boyles is gabbing on the air. In the control booth, Barbara Krieger engineers but, bizarre sight, Gordon Peil, the station's operations director, is serving as programmer, answering the persistent phones, That's like a GS-17 subbing for a GS-5 -- and not from 9 to 5 on weekdays, either. Peil looks dazed, as if he just fell out of bed. His T-shirt reads, "The Opera Is Over -- The Fat Lady Sings," over an ornately visual decal. He answers the calls. "What would you like to talk about? Jazz singers? Okay." . , . "Hang in there, trivia is coming up at the top of the hour." . . . "The Olympics?" . . . "We're heading for 2 oClock -- we'll try to get your call in." Barbara signals Boyles over his headphones, "Sign off at 1:59:31. We've got a 28 1/2 second promo." Boyles nods and keeps talking. Peil answers another call: "I see, I see. What's the name of the book? I see, well, I'll pass it along to Peter Boyles after the show." And another: "Yes, yes. Stay tuned for trivia, right after the news. There'll be two full hours of trivia."

The control-room clock hits 2. I turn to Peil. "Where's the regular programmer?" He answers, "I don't know. Nobody knows. I was home asleep. . ." Boyles rushed in, tells Peil, "Push back trivia to 3 o'clock. From 3 to 5. Right now we've got lots of listeners who want to talk about a dozen other subjects." Boyles dials the outside phone. Waits. Hangs up. "There's no answer at Andrew's place. I'm worried about him. He's not one to miss his shift. I think we should call the police and have them try his apartment." Peil sips coffee, kicks off his loafers, revealing sockless feet, and ponders Boyles suggestion. Then in walks a young man. "Andrew! What happened to you?" Peil asks. Andrew Jones, programmer, solemn and red-eyed, replies, "You won't believe this but it's true: My car broke down." Boyles says, "Let's get this show on the road," and returns to his studio. "Well," Peil turns to Andrew, "get in there -- we're back on the air in 55 seconds." Boyles calls out cheerfully, "Glad to see you, Andrew." Andrew breaks a boyish smile, a face full of creases, "Glad to be here." He dials the phone bank, picks up a call, "Peter will be with you in a moment." Peil scratches the fat lady on his T-shirt and I leave him staring into space, exit past a TV set showing a bizarre disco-fever light show. Spastic dancers in underwear are hooking feet, hips and derrieres, strutting, rolling, flipping and plunging. Like robots. Reminds me of the movie "They Shoot Horses, Don't They?" Also the dance marathone of the 1930s. Donald O'Connor is one of the judges; another judge wears a heavy winter ski cap and leather-patched jacket. Weird.

I amble over to the AP wire. Foreign temperatures. Berlin 52 and cloudy, Casablanca 68 and clear, Hong Kong 82 and cloudy . . . Then to the UPI ticker. "Bandleader Stan Kenton dies in Los Angeles after suffering a stroke. He was 67 years old. Kenton was a jazz innovator and one of the big band leaders." I remember Kenton and his theme, "Artistry in Rhythm." Also I recall he was an indefatigable arm-swinger, touring 52 weeks a year. I feel an urge for normality and swing out the door for the all-night Dart Drug store, Bethesda. 2:50 a.m. Julie Hass is the night cashier; Steve Weber, night manager. "Get any insomniacs?" I ask them."It's slow at night," Steve responds, adding: "But there are people -- only about six or so regulars -- night after night, who come in and buy just one thing. Just a single item." "Only a half-dozen people?" I ask. "That's all." Julie: The men usually go for a five-pack of cigars. The women, a stick of gum or a candy bar. It's an excuse for them to get out. Some just talk and don't buy. Most are older folk. Once in a while one will buy a magazine and talk small talk with us, but there just aren't that many people in here with insomnia." "A lot of 'em look dazed, stroll around and leave as quietly as they came," Steve adds. "They say they can't sleep," Julie says. "I guess they're just loney." I wander around, buy some toothpaste and motor oil and check out. I'm hungry. Maybe a donut shop is open. 3:45 a.m. Janet is alone behind the counter at Montgomery Donuts. She's from Cameroon, West Africa. Two young girls, grimy, come in and buy coffee and "any donuts." The bill is 86 cents. They tip Janet the 14 cents change. "We get fresh donuts in 10, maybe 15 minutes," Janet tells me. "What kind?" I ask her. "I don't know," she says, pointing. "Whatever the signs read." I read them. Apple stix, white coconut, cinnamon twist, devil's food, honey dip and more. I ask Janet about insomniacs and she asks if I want them powdered or plain. A Special Officer enters, two-way radio and a hundred keys on his belt. "I'll talk," he tells me, "but don't use my name." He buys a coffee. I ask, "Do you ever encounter any insomniacs during your all-night tour of duty?" "What's that?" he asks."People that stay up all night." "Yes," he says, "but not too many. Mostly joggers, all night long. Men and women in shorts, sneakers, polo shirts. Not jogging suits. They jog alone, by themselves. We patrol in unmarked cars, cruise along right up to them, slowly, and worry them. Also, mental cases. Outpatients from St. E's and Suburban Hospital. Very rarely breakins, stabbings, cuttings and rape. We look out for crime, but we don't look too hard." "Why not?" "Because," pointing to his hip, "because we're not armed." The fresh donuts arrive. So do about three dozen kids, mostly teenagers. A bunch of them order raspberry-filled powdered donuts and pile them high into their dirty hands. A Montgomery County policeman enters and I try to talk to him. "No quotes," he says, shying away. "I speak French only . . . no quotes." He exits; I follow; Already halfway down the block. I call to him, "Any insomniacs around your beat?" He replies in a shout, "I only speak French." He disappears into his car. So do I, into mine. Maybe the emergency room of Suburban Hospital will yield some bona fide insomniacs. 4:25 a.m. Nine people in the lobby of the emergency room; All look worried, or tired and worried, or tired and drunk, or just drunk. Some stare at the TV set. A guy at the admissions desk queries Joan Ridgway, receptionist, "How's [name]? . ; . He's my friend." "He was discharged." "Is he okay?" he asks her. "We wouldn't discharge him if he wasn't," Ridgeway answers. "Can you tell me where he is?" the guy asks. "I can't say any more," she concludes politely but firmly, and the guy hoofs it to the door as a physician in a green uniform enters and calls a name. A woman responds. She is chunky, wobbly, middle-aged, with a vacant look in her eyes. She thrusts out her lips, puckers like an anteater plunging for a kill, sucks out a mouthful from a diet soda can and follows the doctor beyond the door. "Emergency Room, Miss Ridgway," Joan's on the phone again, then off. "Any insomniacs around here during the night?" I ask her. "Very few. Mostly depressives. Many are suicidal. But tonight it's a night for drunks. Others just wander in like lost souls. They make up any story to talk to people. They'll say, 'I hurt my foot four days ago.' They're full of creative excuses. They just want some conversation. The thing is there are regulars, but so few of them." The green-clad doctor and the diet-soda lady return. He says, "Call a cab for this woman. She can go home, but not alone." The woman puckers her lips around the opening of her diet soda can, sump-pumps a faceful and belches. "She's okay," the doctor assures Joan. For some reason my body seems to be calling for breakfast. I drive to Booneymongers on Wisconsin Avenue. Illustrations 3 thru 7, no captions