Smoking Increases Risks of Sleep Disturbance

5 February 2008

New research by scientists at the Johns Hopkins University School of Medicine shows that cigarette smokers are four times as likely as non-smokers to report feeling tired and not rested after a night’s sleep. The study also revealed that smokers spend less time in REM (deep) sleep and more time in lighter sleep than non-smokers. Researchers think less restful sleep pattern is due to the withdrawal effects of nicotine when the smoker sleeps.

“It is possible that smoking has time-dependent effects across the sleep period,” said study author Naresh M Punjabi, MD, PhD, FCCP, Johns Hopkins University School of Medicine, Baltimore, MD. “Smokers commonly experience difficulty falling asleep due to the stimulating effects of nicotine. As night evolves, withdrawal from nicotine may further contribute to sleep disturbance.”

Dr Punjabi and his fellow researchers compared the sleep patterns of 40 smokers and 40 non-smokers with a home polysomnography. The participants of this study were healthy (free of any significant disease) and were not taking any medication, in order to remove all health factors that could contribute to bad sleep patterns.

The study was also analysed using both a conventional method - visual classification of electroencephalogram (EEG) patterns - and a non-conventional method - power spectral analysis of the EEG, which relies on a mathematical analysis of different frequencies contained within the sleep EEG. These two methods gave a better picture of the sleep patterns of the individuals in the study.

The participants were questioned about sleep quality:

• 22.5% of smokers reported lack of restful sleep
• 5.0% of non-smokers reported lack of restful sleep

The scientific results correlated with the participants report of lack of sleep and this supports the researchers theory that nicotine's effects are strongest in the early stages of sleep and potentially decrease throughout the sleep cycle. The researchers advised that this research may have implications in ways to help people stop smoking.

“The long-term effects of smoking on respiratory and cardiovascular health are well-known,” said Alvin V. Thomas, Jr., MD, FCCP, and President of the ACCP. “However, this study is significant because it suggests that smokers may also be deprived of the much-needed restorative effects of sleep. This study provides yet one more reason to stop smoking or to never start.”

The study appears in the February issue of CHEST, the peer-reviewed journal of the American College of Chest Physicians (ACCP).



Resources
American College of Chest Physicians. Smoking linked to sleep disturbances. Accessed 8 February 2008

Link Between Pregnant Women Smoking and SIDS

A new study by researchers at McMaster University USA, published online in the journal Federation of American Societies for Experimental Biology (FASEB) to be available in the May 2008 print issue, has shed some light on the relationship between women who smoke while pregnant, or are exposed to second-hand smoke, and an increased risk of Sudden Infant Death Syndrome (SIDS) to their babies.

Researchers found out that a specific mechanism is the reason a baby's ability to respond to oxygen deprivation after bith (called a hypoxic episode) is significantly reduced if they are exposed to even light to moderate amounts of nicotine in the womb.

"While cigarette smoke contains many different compounds, we found there is a direct impact of one component, nicotine, on the ability of certain cells to detect and respond to oxygen deprivation," says Josef Buttigieg, lead author and a PhD student in the Department of Biology. "When a baby is lying face down in bed, for example, it should sense a reduction in oxygen and move its head. But this arousal mechanism doesn't work as it should in babies exposed to nicotine during pregnancy."

The research explains the role that specific hormones from the adrenal glands - catecholamines - play in a baby's transition outside the womb and especially it's ability to breath properly.

During the birth, the baby is exposed to low oxygen, which tells the adrenal glads to release the catecholamines (that contain adrenaline), explains Buttigieg.

It is the catecholamines that instruct the baby's lungs to reabsorb fluid, to take its first breath and help the heart beat more efficiently. The adrenal glands still act as an oxygen sensor, for some months after birth, which helps the baby's arousal and breathing responses during periods of apnoea or asphyxia.

The baby's ability to release catecholamines during periods of apnoea or asphyxia (very critical to the baby's ability to survive outside the womb) is very impaired due to the baby's exposure to nicotine while in the womb.

"At birth, the nervous control of the adrenal gland is not active and so a baby relies on these direct oxygen sensing mechanisms to release catecholamines," says Colin Nurse, academic advisor on the study and a professor in the Department of Biology. "But nicotine causes premature loss of these mechanisms, which would normally occur later in development after nervous control is established. Thus, the infant becomes much more vulnerable to SIDS."

The study was funded in part by the Heart & Stroke Foundation of Ontario, Canadian Institutes of Health Research and Focus on Stroke.

References
McMaster University Press Release - 29 January 2008