Cigarettes contain nicotine, which is a stimulant drug that activates the sympathetic nervous system. This causes effects like increased heart rate, blood pressure, and feelings of alertness. So at first glance, it may seem like smoking cigarettes should make you feel more awake rather than sleepy. However, the relationship between smoking and sleepiness is more complex than this.
Nicotine’s alerting effects are short-lived
While nicotine from cigarettes provides an initial jolt of alertness, this effect fades quickly. Nicotine has a very short half-life of only 1-2 hours. This means the stimulating effects of nicotine wear off rapidly as the nicotine is cleared from your body.
So while smoking a cigarette might make you feel more awake for the first 30 minutes after inhaling, this is followed by a nicotine withdrawal phase where you may feel tired and mentally foggy. This up and down pattern with frequent dosing of nicotine during the day can disrupt healthy sleep cycles and make you feel sleepier overall.
Smoking disrupts sleep
In addition to the wearing off of nicotine’s alerting effects, smoking can worsen sleep in other ways:
- Nicotine is a nervous system stimulant that can delay your ability to fall asleep initially.
- Withdrawal symptoms overnight can cause frequent awakenings and restless, fragmented sleep.
- The hundreds of other toxins in cigarette smoke negatively impact sleep quality and health.
- Frequent smoking causes insidious lung and breathing problems that impair oxygen intake while sleeping.
These factors mean that while nicotine may temporarily mask feelings of sleepiness, overall smoking can significantly disrupt the quantity and quality of your sleep. Poor sleep leads to increased fatigue and sleepiness during the daytime.
Smoking withdrawal causes fatigue
When smokers abstain from cigarettes, nicotine withdrawal sets in within just 30 minutes. Withdrawal symptoms include strong cravings for nicotine, anxiety, irritability, and increased appetite. The most common physical symptom is fatigue. Smokers report feeling tired, sluggish, and sleepy when going through nicotine withdrawal.
These withdrawal effects can begin quickly after the last cigarette and peak 2-3 days later. Fatigue and sleepiness may persist at lower levels for weeks after quitting until the brain neurochemistry rebalances. So while cigarettes may seem to provide an energy boost, this masks the underlying exhaustion caused by being in a constant loop of nicotine withdrawal.
Smoking can induce narcolepsy
In rare cases, smoking cigarettes has been associated with onset of narcolepsy symptoms like chronic daytime sleepiness. Narcolepsy is a chronic brain disorder that dysregulates the sleep-wake cycle. It is often tied to low hypocretin levels.
In susceptible individuals, scientists have theorized that certain toxins in cigarette smoke may potentially damage hypocretin neurons and trigger narcolepsy. However, narcolepsy is complex and may also involve genetic and environmental factors.
Case reports linking smoking and narcolepsy
Several case reports have documented apparent connections between smoking and narcolepsy onset:
- A 2014 case described 30-year-old male twins who both rapidly developed narcolepsy symptoms after starting smoking.
- In 2002, a 47-year-old nurse developed narcolepsy about 6 weeks after taking up regular smoking.
- A 2010 patient experienced the onset of narcolepsy symptoms after smoking for 2 years and drinking alcohol daily.
In these unusual cases, cessation of smoking and treatment with stimulants led to improvement in the symptoms. However, these examples represent a small subset of narcolepsy patients. More research is needed on how smoking may potentially damage hypocretin neurons and precipitate narcolepsy in some people.
Smoking worsens sleep apnea
Sleep apnea causes heavy snoring and breathing interruptions during sleep. This leads to poor sleep quality, excessive daytime sleepiness, and an increased risk of accidents.
Smoking is a major risk factor for developing both obstructive sleep apnea and central sleep apnea. It also makes existing cases of sleep apnea worse through these mechanisms:
- Swollen airways and inflammation caused by cigarette smoke increase airway collapse.
- Cigarette smoke impairs lung function and reduces oxygen in the blood.
- Toxins from smoking damage the body’s ability to regulate breathing.
One study found that current smokers have a 3-fold increased risk of obstructive sleep apnea compared to never-smokers. In those with sleep apnea, smoking cessation helps improve their symptoms. So while smoking may make some people feel briefly more alert, it has detrimental effects on their sleep.
Tobacco smoke alters brain receptors
Animal studies suggest that exposure to tobacco smoke can alter receptors in the brain that regulate wakefulness. Specifically, the nicotinic acetylcholine receptors (nAChRs) are involved in arousal pathways.
Inhaled nicotine from cigarette smoke acts on certain subtypes of nAChRs. Researchers found that prolonged exposure to nicotine vapor decreased the sensitivity of the α4β2 nAChR receptors in the brains of rats. These changes were associated with more fragmented sleep patterns.
Through these receptor pathways, smoke exposure may dampen alertness signals and contribute to poor sleep quality and daytime drowsiness. However, more research is needed on this mechanism.
Smoking impacts hormone levels
Smoking also influences important hormones that regulate our sleep and wake cycles like melatonin, cortisol, and growth hormone:
- Melatonin – Nicotine may inhibit melatonin release, making it harder to fall asleep.
- Cortisol – Smoking increases evening cortisol levels, which disrupts sleep.
- Growth hormone – An essential hormone for deep, restorative sleep. Smoking reduces the body’s nightly growth hormone secretion.
Through these hormonal effects, smoking can make it more difficult to fall and stay asleep. The lack of restorative deep sleep then leads to exhaustion the next day.
Cigarettes affect teen sleep patterns
Sleep researchers have found that teen smokers experience more disruption to their circadian rhythm and sleep cycle than nonsmokers. Teens already have a biological tendency to stay up later at night and have difficulty waking for school. But cigarettes exacerbate these problems through several mechanisms:
- Direct stimulation of nicotine late in the evenings.
- Repeated nicotine exposure alters teens’ natural melatonin release.
- Cigarette use is linked to higher evening use of screens like smartphones.
One study tracked sleep patterns in teens for a month using sleep diaries and activity monitors. Teen smokers went to bed about an hour later each night and slept 37 minutes less than nonsmoking teens. They also experienced more irregular sleep schedules between weeknights and weekends.
These types of disruptions during critical adolescent development impairs learning and memory consolidation. Sleep loss also contributes to depression, anxiety and behavior problems in teens.
Trends in teen cigarette and e-cigarette use
While cigarette smoking has declined among American teens since the 1990s, teen nicotine addiction has surged in recent years due to vaping. In 2022, over 2.5 million U.S. middle and high school students reported current e-cigarette use. This represents 14% of high schoolers and 3.3% of middle schoolers.
Teens may incorrectly believe vaping is harmless. But nicotine vapes can disrupt sleep in the same ways as traditional cigarettes. Quitting smoking and vaping allows teens’ brains and bodies to fully mature.
Sleep issues in the weeks after quitting
When heavy smokers first give up cigarettes, they may initially have worse sleep for several weeks. This is due to nicotine withdrawal. Former smokers report:
- Difficulty falling and staying asleep
- Not feeling rested after a full night’s sleep
- Waking up too early in the morning
- Intense dreaming or nightmares
These temporary sleep disruptions are part of the recovery process as the brain’s nicotine receptors reset. Using nicotine patches or vaping may also impair sleep quality during the quitting process. Getting through the first few weeks leads to improved sleep quality, deeper sleep stages, and feeling more energized during the day.
Long-term benefits of quitting smoking
While smoking may provide an immediate stimulation, the long-term effects on sleep and health are overwhelmingly negative. Quitting smoking can dramatically improve sleep and daytime energy levels through these mechanisms:
- Stabilize nicotine levels instead of repeated peaks and crashes
- Reverse nicotine desensitization of wake-promoting receptors
- Improve nighttime oxygen levels and breathing mechanics
- Reduce inflammation that degrades sleep quality
- Rebalance hormones like melatonin, cortisol and growth hormone
One study tested healthy young adult smokers over 4 weeks of abstinence from smoking. Participants subjectively reported fewer sleep problems and less daytime sleepiness. Objectively, their sleep efficiency also improved.
The benefits of quitting smoking continue to accrue over the long term. Former smokers can enjoy deeper, more restorative sleep patterns that leave them feeling refreshed, focused and energized throughout their waking hours.
Conclusion
While smoking cigarettes may provide an initial short-lived stimulation, the overall effects lead to poorer sleep quality and increased sleepiness for most smokers. The direct effects of nicotine and withdrawal disrupt healthy sleep cycles. And cigarette smoke harms sleep through effects on breathing, hormones, and brain receptors.
Teen smokers face particular risks of disrupting their critical circadian rhythms and sleep patterns during development. While quitting can cause some temporary sleep disturbances, these resolve within a few weeks. In the long run, smoking cessation allows former smokers to enjoy improved sleep quality, longer sleep duration, and increased daytime energy.