When it comes to sleeping habits, a new study shows Americans are like night and day. About half have generally healthy habits but the other half struggle to get a good night's sleep.

For the first time, researchers at the National Sleep Foundation used information from their annual Sleep in America Poll to divide American adults into five distinct sleep profiles based on their sleeping habits.

Nearly half (48 percent) of the poll respondents fell into one of two “good sleeper” categories, while the other 52 percent fell into three “not so good” sleeper profiles. Researchers say people should identify the group that best describes them and look for ways to improve their sleeping habits.

The five groups are based on more than 40 factors including how many hours slept per night, frequency of experiencing a sleep problem, how often they feel tired, number of caffeinated beverages consumed daily, and other sleep-related habits.

The five sleep categories include:

Healthy, Lively Larks

This is the largest as well as the youngest of the five sleeper profile categories, accounting for 27 percent of the poll respondents with an average age of 45. They are least likely to be affected by sleep problems, either of their own or their spouse/partner.

—Most (75 percent) say they usually get a good night’s sleep.

—Two-thirds say they get more sleep than they need, and most never/rarely feel tired/fatigued.

—Most are married/partnered and working full time at regular day shifts. They consider themselves “morning people” (“larks”), and 77 percent of them are up by 7 a.m. during the week.

—They fall asleep faster than the other groups, with 65 percent reporting that they fall asleep in less than 15 minutes. They are less likely than other groups to have a diagnosed medical condition.

Sleep-Savvy Seniors

The oldest of the five groups with an average age of 60, this group represents about 21 percent of adults. They get the most sleep of any group, averaging 7.3 hours per night compared to 6.8 overall.

—Nearly three-quarters (74 percent) say they get a good night’s sleep on most nights.

—Nearly half (46 percent) take two or more naps during the week.

—Most never/rarely feel tired/fatigued (69 percent).

—Many have been diagnosed with at least one medical condition; they do not feel they have a sleep problem and are less likely than other groups to be at risk for any sleep disorder.

—People in this group are the most likely to be retired (51 percent) and least likely to be employed (30 percent); two-thirds are female.

Dragging Duos

This group, the largest of the “not so good” sleeper groups, accounted for 20 percent of the poll respondents. More than the other groups, the “dragging duos” are most likely to be married or living with someone (80 percent), employed (76 percent), and working more than 40 hours a week (55 percent).

But those habits may be robbing them of valuable sleep.

—30 percent say they do job-related work within an hour of going to bed, a practice not considered a good sleep habit.

—During the week, most (72 percent) are out of bed by 7 a.m. But they try to make up for lost sleep by sleeping an hour longer on weekends than on weekdays.

—They are nearly twice as likely as the other groups to get less sleep than they say they need to function at their best (41 vs. 23 percent), and more than one-third say they feel tired/fatigued at least three days each week.

—Most say that their partner has at least one symptom of insomnia (92 percent).

—Their partner’s sleep disorders, or their own, have caused some problems in their relationship, and about one-fourth say their intimate relationship has been affected because of sleepiness.

Overworked, Overweight, and Overcaffeinated

The second of the “not so good” sleeper categories accounts for 17 percent of adults, many of whom (56 percent) consider themselves night owls.

—These mostly male night owls are employed and have the longest work week (47 hours compared with 42 hours overall), although they are least likely to work regular day shifts.

—They sleep less than other groups (5.2 hours per night) but nap more, with two-thirds taking two or more naps each week.

—They feel they need fewer hours of sleep each night to function at their best (5.2 hours), and nearly half say they get more sleep than they need.

—Members of this group drink more caffeine than other groups (4.0 cups/cans vs. 2.8 overall).

—Seven in 10 frequently experience a symptom of insomnia, and a smaller ratio says that they frequently get a good night’s sleep.

—About half of this group is single, and the same percentage would be classified as obese.

Sleepless and Missin’ the Kissin’

This last group has the largest proportion of night owls (59 percent) and accounts for about 15 percent of adults overall. They are the least likely to say they frequently get a good night’s sleep, and 58 percent think they have a sleeping problem.

—Nearly half feel they are getting less sleep than they need, and the same number say they usually feel tired or fatigued.

—They are more likely than other groups to say their (or their partner’s) sleep disorders have caused significant or moderate problems in their relationship.

—More than twice as many (42 percent) of the people in this group also say being too sleepy has negatively affected their intimate relationships versus 19 percent overall.

—Most of this group has been diagnosed with a medical condition (84 percent), and they are more likely than other groups to use sleep aids.

—Only half of people in this group are employed, and there is a high number of females. Half say their doctor has asked them about their sleeping habits compared with 29 percent who have been asked overall.

By Jennifer Warner, reviewed by Brunilda Nazario, MD

SOURCES: 2005 Sleep in America poll, March 29, 2005, conducted for the National Sleep Foundation by WS&A Market Research based on a random sample of 1,056 adults interviewed by phone between Sept. 20 and Nov. 7, 2004. Press releases, National Sleep Foundation.