If television is the single most effective, if not the least addictive, soporific known to allegedly civilized man, it has rarely explored the subject of sleep itself. The record stands corrected in basically fine fashion tonight by "Sleep From A to Zzzzz," a diverting documentary at 8 on Channel 5.

There are few faults to the program that couldn't have been cured with a bigger budget; Metromedia is not known as a company that diverts its enormous profits into such luxuries as program production. But producer Pola Miller worked a minor miracle or two in coming up with an hour that looks and sounds as good as this one does.

From time to time, the program tries a little too hard to be entertaining with its information -- the sympton, usually, of too little faith in the material and/or too little faith in the innate curiosity of the audience. So much is happening in sleep research and so little of it has been exposed on television that there's probably more cuteness here than necessary.

Tony Randall, however, makes an ideal guide through the tour of our darkest hours, those hundreds we spend in lullabye land, and the great efforts some people have to expend in order to get there. Producer Miller visits a sleep lab where insomniacs are rerouted into new time patterns that will enable them to catch elusive winks they've sought for years.

Patients are locked in isolated rooms away from all the usual clues as to what time of day it is. Then their sleeping and waking patterns are readjusted. All this is explained on the program by Dr. Elliot D. Weitzman of the Montefiore Hospital's Sleep-Wake Disorders Center. Unfortunately, Dr. Weitzman is a man blessed with an abundance of fascinating information and cursed with the ability to make it ferociously dull. Some of the other experts interviewed would have been better off reclining peacefully on the cutting room floor, their revelations entrusted to Randall, or Miller herself, or someone else with a more pronounced knack for communication.

Miller's harangue against sleeping pills is unnecessarily moralistic and not backed up with sufficient authority. She also chooses, mysteriously enough, to go off on a capricious tangent about the frequency of male erections during sleeping -- a relatively frivolous diversion when one considers the other points about sleep that are insufficiently investigated.

But then the hour is only an introduction, and if here and there the editorial decisions are a trifle eccentric, the program does leave one in a pleasant state of heightened awareness and cheered amusement. There won't be many people who can't empathize with the troubled patient who recalls of her insomniacal spells that when tossing and turning, "You think the whole world is resting and asleep and I'm the only one awake."