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If your love for coffee runs deep, but you're worried about you favourite beverage keeping you awake at night, life is about to get better.
A new study has found that nicotine and alcohol use within four hours of bedtime was negatively associated with the quality and quantity of subjects' sleep, while coffee and other caffeinated beverages didn't significantly affect their chances of catching a good night’s sleep – in most cases anyway.
The researchers do warn, however, that some individuals are more sensitive to caffeine than others, and that caffeine can still make a difference to some people's sleeping patterns.
The study, published in the journal Sleep, examined the consumption of alcohol, caffeine and nicotine among 785 African-Americans over a period of 5 164 days and recorded sleep outcomes in their natural environments. Participants also recorded how much alcohol, caffeine or nicotine they had consumed within four hours of bedtime. The results were observed in individuals unselected for sleep problems, and who generally had high sleep efficiency.
The study was led by a researcher at Florida Atlantic University with collaborators from Brigham and Women's Hospital, Harvard T. H. Chan School of Public Health, Harvard Medical School, Emory University, the National Institutes of Health, and the University of Mississippi Medical Center. It is one of the largest investigations to date to examine the consumption of these three substances and their effect on sleep.
A terrible quality of sleep
Having a drink or smoke before bed is fairly common and might help you to fall asleep faster – but it won’t necessarily be restful sleep.
The study noted worse sleep continuity when participants used alcohol or nicotine, compared to a night without these substances. The results remained fixed regardless of age, gender, obesity, depressive symptoms and other factors.
If you needed greater incentives to quit, here’s another one – nicotine was found to be most strongly associated with sleep disruption. If you already suffer from insomnia, the effects could hit you even harder. According to the results, using nicotine at night leads to more than a 40-minute reduction in overall sleep duration.
Sleep deprivation and health problems
According to Science Daily, up to 70 million Americans have a sleep disorder. While there are no statistics for South Africa, it was reported last year that sleep-deprived South Africans cost the economy billions each year, and insufficient sleep is linked to 15 leading causes of death, including heart disease and certain cancers.
Apart from this, chronic sleep deprivation could potentially affect your sex drive (especially in women), and cause depression and obesity in the long run. Short-term problems include impaired memory, a reduced quality of life and an increased likelihood of causing accidents, a previous Health24 article notes.
Skimping on sleep has also been linked to premature skin ageing, depression and ADHD in kids, and negative effects on metabolism.
Past studies
Past studies have found that evening consumption of alcohol, caffeine and nicotine leads to disrupted sleep, but many aspects weren’t thoroughly investigated, were limited by small sample sizes and weren't racially or ethnically diverse.
"African Americans have been underrepresented in studies examining the associations of nicotine, alcohol, and caffeine use on sleep," said Christine Spadola, lead author and an assistant professor in FAU's Phyllis and Harvey Sandler School of Social Work within the College for Design and Social Inquiry.
"This is especially significant because African Americans are more likely to experience short sleep duration and fragmented sleep compared to non-Hispanic Whites, as well as more deleterious health consequences associated with inadequate sleep compared other racial or ethnic groups."
Moreover, past studies were conducted in laboratory or observatory settings, whereas this study involved concurrent actigraphy – a non-invasive method of assessing participants’ sleep. A wrist watch-like sensor and daily sleep journals were used to assess sleep duration, sleep efficiency and wakefulness after sleep onset.
In order to improve sleep, the researchers' findings support the restriction of evening alcohol and nicotine use.
