Knit Blog

Studies have shown that psychoactive substances affect sleep, each one in a vastly different way. Here’s a deeper dive into the substances that disrupt our sleep.

Caffeine and Sleep

As the brain uses energy, it produces a sleepiness molecule call adenosine, which tells the brain that it needs to sleep in order to replenish its energy stores. Caffeine helps improve alertness by blocking the signal from that molecule, effectively tricking the brain into thinking that it no longer needs to sleep. Overall, the sensitivity to caffeine, and the amount of time it remains in the body, varies quite significantly from person to person.

Caffeine from a natural source, such as coffee or tea, may actually potentially be beneficial for health in moderation. In some individuals, it may have antidepressant effects, and there have been numerous studies that show a reduction in the overall mortality rates of coffee and tea drinkers vs. non-drinkers. The same can’t be confidently said of pure caffeine, such as a caffeine pill, caffeinated drinks, such as soda or energy drinks. Studies have shown, however, that artificially sweetened beverages, including those with sugar substitutes such as those in “diet” soda, seem to be associated with higher mortality and worsened health.

If You Don’t Consistently Consume Caffeine

Having any during the day (even in the morning) has the potential to delay sleep onset night and reduce your sleep quality. Once your brain becomes accustomed to its daily dose of caffeine though, those effects on sleep are lessened, but don’t completely disappear. The closer to bedtime that you consume caffeine, the more likely it is to impair your sleep quality. People don’t always notice the reduction in their sleep quality though, so they incorrectly assume that nighttime caffeine doesn’t affect them. However, a detailed analysis of their sleep often reveals the reduced quality of their sleep. Unfortunately not everyone gets these analyses on a regular basis so they maintain their misperception.

If You Consistently Consume Caffeine

Reducing or abstaining on a given day is likely to result in withdrawal symptoms, which can include headache, fatigue, depression, lack of motivation and/or sleepiness. Even more unfortunately, caffeine withdrawal can last over a week in some individuals after they stop consuming caffeine entirely, particularly if they were consuming high levels at the outset.

What I Recommend:

  • Be consistent with the timing and amount of caffeine you drink each day.
  • If you habitually consume caffeine, get it from a natural source such as coffee or tea, not sodas or energy drinks.
  • You can strategically supplement an extra “dose” of caffeine if needed for a boost of alertness. If you do this for more than 2 days in a row, though, you may experience withdrawal symptoms (headache, fatigue, depression, lack of motivation, sleepiness) after going back to your typical amount. Also, if you do consume an extra dose of caffeine, you may experience worsened sleep quality or difficulty falling asleep that evening (particularly the closer that dose is to your bedtime). And you may not be aware of the reduction in sleep quality.
  • If you habitually feel that your sleep quality is poor or fragmented or experience difficulty falling asleep, consider eliminating all caffeine after 12pm (the exact time varies between individuals). You can also experiment with eliminating caffeine entirely.
  • If you experience frequent urination during the day or night, consider reducing your caffeine intake or stopping entirely.
  • If regularly counteract an afternoon “dip” with caffeine, try stopping that caffeine dose entirely. Sometimes part of that “dip” is actually caffeine withdrawal and the dip may improve after 1-2 weeks without your afternoon dose.

Nicotine and Sleep

Nicotine is a central nervous system stimulant found in natural sources of tobacco such as cigarettes, cigars and chewing tobacco. It can also be found in non-natural tobacco replacement products such as vaping fluid and nicotine gum/lozenges/patches. Because nicotine is a stimulant, it increases alertness, so using nicotine-containing substances before or during the night will reduce sleep quality. Further disrupting sleep quality, chronic users of nicotine can experience withdrawal after only hours because nicotine has a short duration of action. Smoking and chewing tobacco products have been linked to a large number of long-term adverse consequences and quitting usage is recommended. The long-term consequences of nicotine replacement products is unknown at this time.

What I Recommend

  • If you currently smoke or chew tobacco, consider quitting for overall health and sleep benefits.
  • If you use nicotine in other forms, be aware that use of these products may reduce your sleep quality if used within several hours of bedtime or during the night.
  • For more information on how smoking affects sleep, this article goes into greater detail.

Alcohol and Sleep

Alcohol contains ethanol, which is sedating to the central nervous system. Due to this effect, alcohol is commonly used by the general population to help induce sleep. It turns out, however, that ethanol actually disrupts the function of the body’s internal clock, reducing sleep drive in the second half of the night and potentially reducing daytime alertness the following day. It also reduces the Rapid Eye Movement (REM) stage of sleep, which is essential to proper processing of information learned during the day, emotional regulation, immune system and cardiovascular function. Chronic suppression of REM, which can occur with chronic, heavy alcohol use, can lead to impairment of these and other biologic functions. Ethanol causes increased urination at night, leading to more wake-ups and disrupted sleep.

Additionally, as alcohol is metabolized by the liver, other substances are produced which worsen sleep quality in the second half of the night, leading to an increased number of arousals. Ethanol and these other chemicals can worsen sleep disorders such as obstructive sleep apnea and restless leg syndrome. Even when ingested 4-5 hours before bed, several studies have still shown detectable effects on nighttime sleep quality. Chronic alcohol users who stop using alcohol typically experience severe sleep disruption initially which is often followed by chronic complaints of insomnia.

What I Recommend

  • If you regularly ingest alcohol and are experiencing poor sleep quality, consider stopping alcohol use for several months to see if it improves.
  • Try to consume alcohol at least 4 hours before bedtime to reduce the effects on your sleep.
  • If you do not choose to stop consuming alcohol, reducing your alcohol intake and moving it to slightly earlier in the evening may still benefit your sleep.
  • If you ingest large amounts of alcohol, you should speak with a medical provider about the decision to stop drinking, and be aware that your sleep may severely worsen before improving.

Cannabis and Sleep

Due to the previously illegal nature of cannabis, high quality data on the effects of cannabis on sleep are lacking. Nevertheless, several observational studies have shown that habitual cannabis users report increased sleep disturbances compared to non-users or occasional users. Additionally, cannabis has a very long elimination half-life (25-36 hours), meaning that residual effects will still be present after waking up and is therefore going beyond the parameters of a sleep aid. In daily recreational users, THC can be detected for 1 month or more after cessation of use. Cognitive function may be affected throughout and even beyond this time period due to delayed withdrawal effects once all cannabis compounds have been fully cleared from the brain and body.

What I Recommend

  • Cannabis is not recommended as a nightly sleep aid at this time due to a very long duration of action, the potential to actually worsen sleep disturbances over time, and unproven benefits.

All Sources:

  • The effects of cannabinoid administration on sleep: a systematic review of human studies. Gates PJ, Albertella L, Copeland J. Sleep Med Rev. 2014 Dec;18(6):477-87.
  • Marijuana use patterns and sleep among community-based young adults. Conroy DA, Kurth ME, Strong DR, Brower KJ, Stein MD. Addict Dis. 2016;35(2):135-43.)