This is it. Christmas shopping for insomniacs. The vast parking lot outside Zayre in Camp Springs is bathed in bright yellow light and littered with more than two dozen cars. Inside, shoppers prowl the toy aisles, pick over the plastic angels and tinsel garlands, and stack jumbo rolls of wrapping paper into their carts.

A voice on an intercom requests a price check at Register 2. A peppy instrumental version of "Rudolph the Red-Nosed Reindeer" rings out over the store.

It is 4 a.m. Do you know where your credit cards are?

As usual, the Zayre Corp.'s 338 discount stores in 24 states and the District are open 24 hours through Christmas Eve. Such a bold gesture must mean that the corporate minds involved expect holiday shoppers at all hours. But who would want to be browsing, not drowsing, at 4 o'clock in the morning?

This, after all, is not the sprightly 2 a.m. hour of carousers. Nor is it the 6 a.m. time slot when the chipper early birds might be aloft with itemized lists in hand.

This is the lonesome, lowdown time of night -- when the streets are deserted and surreal, when the houses are dark and hushed, and when scrawny dogs take one last howl at the moon before bounding off to spread garbage over lawns.

It is also an optimum time to purchase Christmas foil and Tonka toys, agreed Anita Bennerman and LaSonya Dockery. Consider the advantages of their predawn shopping excursion: Plenty of parking close to the store, plenty of elbow room, no jockeying for position in the toy aisles, and no long irksome wait in the checkout line.

"Oh, it's crazy, all right," said Bennerman, 19, of Temple Hills, who ventured to Zayre after completing a night's work at a local carrier company. "You don't ever find me up at 4 o'clock in the morning. Uh-uh. This is not my hour."

"But it is a lot of fun, if you can stay awake," said Dockery, 22, also of Temple Hills. "Sort of gets you in the Christmas spirit somehow."

Shopping in the predawn hours is apparently an adult pastime.

Not a single child was shopping at Zayre at 4 a.m. on a recent Saturday. The Rambo M-24 Dart Gun with machine-gun sound was silent. The Sesame Street Big Bird for Baby played no lullabies. In the middle of an aisle, however, a middle-aged woman in a pink sweat suit repeatedly forced a talking Tweetie Bird to squawk, "Goodness gracious, goodness gracious," by pulling its string. The music-to-shop-by featured "Jingle Bells" and then switched to a chorus of "O Little Town of Bethlehem."

It's true that the movements of the shoppers in the two-level store seemed a tad lethargic -- not the average bustling prime-time crowd. A man holding a 7-Eleven coffee cup yawned as he sorted through a rack of pocketbooks. A young woman in a red down coat trudged through the decorations department, dragging a young man by the hand. A store clerk doggedly priced stacks of plaid flannel shirts.

While her family slept, Donna Greer of Clinton had braved the windy, freezing morning to search, unhindered, for toys, gloves and underwear. Now she stood with list in hand, ready to shop at leisure and looking admirably alert. "My sister and I decided to do this together," said Greer, 37, who spends her days working as a budget technician for the Department of Justice. "But I woke up late, if you can call it that, and she had already come and gone.

"It's easier shopping this time of night," she said. "You have your freedom. You feel like the store belongs to you. You can see what you want and you can see what you don't want."

And what next? Would Greer return to the snug warmth of her bed, smug in the knowledge that she had outfoxed the holiday crowds?

"No," she said, wheeling her cart around as "Hark, the Herald Angels Sing" trumpeted through the store. "I'll be shopping all day."