The genes behind sleep patterns

When the alarm goes off at 6:30 a.m., are you the type of person who leaps to their feet, goes for a brisk run and then whistles in the shower? Or do you wince, flip over in bed and pull the sheets over your head, hoping for a few extra minutes of shut-eye?

Whether you're a morning person or a night person depends on your genes, new research suggests. That means that despite your best efforts to rise and shine or stay up to watch that late movie your genetic makeup may be working against you.

It also means that when daylight time kicks in, it can be a painful adjustment for people regardless of which category they fall into. That's because the body's internal clock, the circadian rhythm, is disrupted.

Circadian rhythm

Sleep is regulated by two mechanisms: circadian and homeostatic. Circadian regulation affects the timing of sleep, while the homeostatic mechanism affects a person's need for sleep.

Circadian rhythm can be changed during periods of daylight time. However, it is only able to change slowly.

When German researchers examined people during daylight time in both the fall and spring, they found that moving a wakeup time by an hour forward or back had significant effects.

"When we implement small changes into a biological system which by themselves seem trivial, their effects, when viewed in a broader context, may have a much larger impact than we had thought," said Till Roenneberg of Ludwig-Maximilian-University in Munich, Germany, an author of the 2007 study, in a release.

"Our results show that the human circadian clock does not adjust to the daylight saving time transition," Roenneberg said, adding that this is most pronounced in the spring.

Sleep gene found

The idea thatsomeone canchangehis or hermorning or night person status is pretty widespread. People who couldn't get up in the morning are often seen as lazy, while those who go to bed "with the chickens" are seen as boring the types who can never last during a night on the town.

In 2001, however, that thinking was turned upside down at least scientifically. That year, researchers at the University of Utah zeroed in on a sleep gene called hPer2, found only in people who chose to go to bed at 7 p.m. and slept until 4 a.m. It was a finding that brought to light the fact that genes are responsible for a person's sleep preferences, rather than conditioning or adaptation to one's environment.

The genetic links kept coming. In 2003, British scientists identified a gene called Period 3 which is involved in regulating a person's internal clock. In early-morning types, the gene is longer in length, while in people who prefer to stay up late, the gene is shorter. Then in 2009, the same Utah research group that found the hPer2 gene discovered the first circadian rhythm sleep gene implicated in short sleep, called DEC2-in "short" sleepers. People possessing this gene require only six to 6.6 hours of sleep per night.

Recent research out of the Centre for Narcolepsy at Stanford University suggests narcolepsy a chronic sleep disorder that causessufferers tobe extremely tired during waking hours and often fall asleep instantaneously at inopportune times is caused by the lack of two brain-related chemicals called hypocretin-1 and -2.

The cells that create those chemicals are missing in the brains of narcoleptic patients. The most likely explanation may be that those cells are destroyed in some sort of auto-immune attack, the school suggests, but more research is needed. Most people withnarcolepsy have a gene called HLA-DQB1*0602. It's unclear whether it's a causal relationship or whether it may one day lead to treatment, but still an encouraging signfor theone in 2,000 people who suffer from narcolepsy.

Not enough sleep

A surprising number of Canadians (40 per cent) claim they're "morning people," according to a 2007 Environics study commissioned by the Better Sleep Council Canada, meaning their peak alertness is between 6 a.m. and 9 a.m. Twenty per cent are very early morning people, rising between 3 a.m. and 6 a.m.

While they may rise and shine, people in this group, along with their nighthawk counterparts the 15 per cent of the population that goes to bed between midnight and 3 a.m. still don't get enough sleep. Though most Canadians in the study may go to bed around 10 p.m. and wake up just before 7 a.m., many have their sleep interrupted by street noises, children, pets and uncomfortable beds. As a result, one in four describe themselves as sleep-deprived.

And lack of sleep has been linked to diseases and conditions such as diabetes, heart disease, certain cancers and mood disorders. It can also lead to obesity, as chronically sleep-deprived people eat to obtain the energy they didn't get from sleep, snacking on high-energy and high-fat foods during the mid-afternoon slump to stay awake.

People who don't get adequate sleep are also more prone to accidents, which peak during daylight time periods, according to scientists.American researchers have found that on the Monday after daylight time change, there is a surge in the number of accidents. In a study of miners, they discovered that accidents went up 5.7 per cent, and that injuries from those accidents resulted in a spike in days off work of 67.6 per cent.

Changing your sleep pattern

Changing one's sleep patterns can be achieved to a certain degree, regardless of genes. It just requires careful planning. Many experts feel that any time a change in sleep patterns is expected, as with a switch to or from daylight time, it's a good idea to readjust your sleep schedule six days prior, by shaving 10 minutes off your regular bedtime each night, or 15 minutes per night for four nights before the time change.

Some also suggests eating meals in a similar manner bumping up breakfast, lunch and dinners by certain time increments. And many recommend skipping naps to prevent interference with the body's circadian rhythm.

Taking the supplement melatonin, a hormone produced by the pineal gland, can also help reset an internal clock. This supplement must be taken four or five hours before bedtime to work effectively, however.

And exercising earlier in the day not late at night can also help prevent a surge of energy when you need it least: just before bed.