Scientists have linked the smoking of cigarettes specifically to the development of several serious cancers, heart disease, routine infections, anxiety and depression. While the toxic chemicals and heavy metals consumed during smoking are to blame for these destructive health risks, nicotine -- the substance that makes smoking so addictive -- is often disruptive to another aspect of health entirely: sleep. Smoking regularly can wreak havoc on the body's natural sleep routine, and some of that damage cannot be undone.

Here are six ways smoking destroys the quality of your sleep.

Smoking changes your natural circadian rhythm.

A 2013 study from researchers at the University of Rochester Medical Center found that smoking tobacco can alter the expression of clock genes in both the lungs and the brain, thus ruining a restful night's sleep. After exposing mice both chronically and acutely to cigarette smoke, the researchers noticed a substantial disruption of their natural circadian clocks, which only worsened with increased tobacco exposure. The consequences of this disruption of circadian rhythms moved beyond poor sleep to include risks of developing depression, anxiety and various mood disorders.

Smoking increases your risk of developing sleep apnea.

According to a 2011 study, people who currently smoke are 2.5 times more likely to also suffer from obstructive sleep apnea, the most common type of sleep apnea caused by the collapse of muscles in the back of the throat during sleep. Smokers experience this repeated cessation of breathing more often because the smoke they inhale irritates the tissues in the nose and throat, causing swelling that further restricts air flow.

Smokers wake up more frequently during the night.

In 2008, scientists at Johns Hopkins University studied the sleep patterns of 40 smokers and 40 nonsmokers. Of the nonsmoker participants, 5 percent said they commonly experienced restless sleep, whereas 22.5 percent of the smokers said they struggled with restless sleep. Then, using an electroencephalogram (EEG) to monitor participants' sleep at home, the researchers found the smoking group accumulated more light sleep than the nonsmoking group, while the nonsmoking group experienced more restorative, deep sleep.

Smokers have trouble falling asleep, and feel restless in the morning.

Similar to caffeine, nicotine is both a drug and a stimulant, meaning it can substantially affect the quality of your sleep if consumed in high quantities and too close to bedtime. According to a 2013 University of Florida study, the average person loses 1.2 minutes of sleep for every cigarette they smoke, due to nicotine's stimulating and subsequent withdrawal effects, Men's Health reported. People who smoke within two hours of bedtime struggle to fall asleep because the nicotine disrupts their natural sleep-wake cycle, and withdrawal symptoms set in before the morning alarm goes off, often leaving smokers feeling even more restless and agitated.

Smokers are more likely to suffer from insomnia.

According to the National Sleep Foundation, insomnia can be caused by an array of psychiatric and medical conditions, as well as lifestyle habits. Because nicotine is a potent stimulant, cigarette smokers can easily develop insomnia if they smoke frequently and close to bedtime. And one study found that women in late mid-life who smoke are even more susceptible to developing insomnia.

Once you start smoking, your sleep will never be the same again.

Putting an end to your smoking habit will do wonders in recovering the quality of your sleep. However, let it be known that people who have never smoked at all prove to be the soundest of sleepers. Yes, there's room for improvement after quitting, but, for many reasons, it's best never to start.