Pulling all-nighters to meet deadlines or working the graveyard-shift to make ends meet could an adverse affect on one's health.

Working at night or irregular shifts keeps workers from getting the regular snooze time that most daytime workers take for granted. These workers could also develop shift work sleep disorder (SWSD).

People with the disorder have higher rates of absenteeism and accidents related to sleepiness.

"We don't see a lot of people who do fine on shift work," Sally Ibrahim, MD, of the Cleveland Clinic's Sleep Disorder Center, told WebMd."They have trouble sleeping, trouble waking. And they're drowsy when they're awake."

Routinely staying up late or working the graveyard shift forces the body to operate counter to its circadian rhythm, the body's internal clock that regulates the timing of periods of sleepiness and wakefulness throughout the day.

It's not uncommon for people with such schedules to suffer from SWSD, which is characterized by insomnia and excessive sleepiness. .

Wesley Elon Fleming, MD, director of the Sleep Center Orange County in southern California, told WebMd that memory and ability to focus can become impaired and are usually irritable or depressed. A person's relationships and social life can suffer, too.

Ibrahim said the lack of sleep is also linked to anxiety, substance abuse and other mood disorders.

Some of the problems these workers face are potentially life threatening. According to WebMd, those who work nights or irregular shifts seem to have a higher risk of ulcers, insulin resistance, metabolic syndrome and heart disease.

Ibrahim said that in order to make working odd hours easier, workers should make gradual changes to their circadian rhythms as opposed to abrupt ones. She said it takes at least two days ­-and perhaps as much as a week -to adjust to a major shift in schedule.

She also said these workers should avoid caffeine, as it is likely to raise their sleep deficit.