Alcohol and Sleep: How Your Nightcap Might Be Sabotaging Your Rest

blog written by Abby Jo Vanderfin, Cal Poly, San Luis Obispo former undergraduate intern supervised by Dr. Hannah Roberts

A glass of wine after a long day, a margarita by the pool, cracking open a cold one after work… alcohol is commonly associated with relaxation and unwinding. It’s no surprise that some turn to alcohol as a sleep aid. After all, it can make you feel drowsy and help you fall asleep faster.

But here’s the catch: alcohol actually disrupts your sleep more than it helps. While it might help you doze off initially, it fragments sleep, suppresses REM sleep, and can leave you feeling exhausted the next day (Ebrahim et al., 2013).

If you’ve ever woken up at 3 AM after drinking, staring at the ceiling or feeling restless, you’ve experienced this firsthand. Let’s explore why alcohol disrupts sleep, how other substances (like cannabis, caffeine, and blue light) can also play a role in disrupting sleep, and how you can create a wind-down routine that actually works.

How Alcohol Disrupts Sleep

1. Alcohol Reduces REM Sleep

REM sleep (Rapid Eye Movement) is the phase of sleep when your brain processes emotions, consolidates memories, and repairs itself. It’s essential for waking up feeling rested, mentally sharp, and emotionally balanced.

Alcohol, however, suppresses REM sleep, meaning you wake up feeling foggy, forgetful, or just "off" (Ebrahim et al., 2013). The more you drink, the more REM sleep you lose.

2. It Causes Choppier Sleep

Ever notice that after a few drinks, you wake up multiple times during the night? That’s because alcohol disrupts your sleep cycles, making your rest choppier and less restorative, known as sleep fragmentation (Roehrs & Roth, 2001).

Even if you technically get 7-8 hours of sleep, it’s not the deep, uninterrupted sleep your body needs.

3. It Can Worsen Sleep Apnea & Snoring

Alcohol relaxes the muscles in your throat, which can make breathing more difficult. If you snore—or if you have undiagnosed sleep apnea—alcohol makes it worse (Stein & Friedmann, 2005).

That’s why after a night of drinking, some people wake up gasping for air or feeling like they barely slept.

4. It Throws Off Your Internal Clock

Your circadian rhythm (your body’s internal clock) is designed to keep you alert during the day and sleepy at night. Alcohol, however, disrupts this rhythm, making it harder to fall asleep and leading to early awakenings (Brager et al., 2021).

The result? You might wake up too early feeling restless, anxious, or still tired.

Bottom line: Alcohol may help you fall asleep faster, but it lowers sleep quality, leaving you exhausted and unrefreshed the next day.

How Regular Alcohol Use Affects Sleep Over Time

If you drink regularly, even in moderate amounts, alcohol’s effects on sleep compound over time. Many people don’t realize that habitual drinking can lead to chronic sleep disruptions, even if they don’t feel the immediate effects.

1. Less Deep Sleep & More Light Sleep

• With consistent alcohol use, your body adapts by reducing deep, restorative sleep and replacing it with lighter sleep (Feige et al., 2006).
• Over time, this can increase fatigue, weaken immune function, and affect cognitive performance.

2. Increased Risk of Chronic Insomnia

• Habitual drinking is linked to higher rates of insomnia, with some studies suggesting that over 35% of people with alcohol dependence experience chronic sleep problems (Brower, 2015).
• This creates a vicious cycle: alcohol leads to poor sleep, which increases stress and fatigue, which then triggers the urge to drink again. 

3. Worsening Sleep Fragmentation Over Time

• Initially, alcohol helps with falling asleep, but as tolerance builds, it no longer has the same sedative effect.
• Instead, you may experience more nighttime awakenings and difficulty staying asleep (Koob & Colrain, 2020).

4. Alcohol-Induced Sleep Apnea & Snoring

• Even for moderate drinkers, alcohol increases the risk of sleep apnea – a condition where breathing repeatedly stops during sleep (Stein & Friedmann, 2005).
• This means less oxygen to the brain, poorer rest, and grogginess the next day.

Key takeaway: The more consistently you drink, the more alcohol interferes with sleep patterns over time. Cutting back—even slightly—can lead to measurable improvements in sleep quality and overall well-being.

Other Substances That Affect Sleep

Cannabis

• Short-term: THC can make you drowsy, helping you fall asleep faster (Schierenbeck et al., 2008).
• Long-term: Regular cannabis use can reduce REM sleep, meaning less restorative dreaming and cognitive processing (Babson et al., 2017).
• Withdrawal: If you use cannabis regularly and stop, rebound insomnia and vivid dreams can disrupt sleep for weeks (Babson et al., 2017).

Caffeine 

• Caffeine has a half-life of 5-6 hours, meaning that an afternoon coffee can still affect your sleep at night (Drake et al., 2013).
• It blocks adenosine, the sleep-promoting chemical, keeping your brain wired and awake longer than you realize.

Nicotine 

• Nicotine is a stimulant, increasing heart rate and alertness, making it harder to fall asleep and stay asleep (Jaehne et al., 2009).
• Studies show smokers experience more night wakings and lighter sleep compared to non-smokers (Jaehne et al., 2009).

The Impact of Screens & Blue Light on Sleep

Suppresses Melatonin Production

Melatonin is the hormone that tells your brain it’s time to sleep. Blue light from phones, TVs, and tablets suppresses melatonin, making it harder to fall asleep (Chang et al., 2015).

Tricks Your Brain Into Thinking It's Daytime

Your circadian rhythm is light-sensitive, meaning screen exposure at night confuses your body clock (Cajochen et al., 2011). This can lead to delayed sleep onset and restless sleep.

Bottom line: Cutting down blue light exposure 1-2 hours before bed can dramatically improve sleep quality.

How to Create a Restorative Wind-Down Routine

3. Set a Consistent Bedtime: Going to sleep at the same time daily helps regulate your circadian rhythm (Czeisler & Gooley, 2007).
4. Reduce Evening Stimulants: Cut out caffeine and nicotine in the afternoon/evening to help your body relax naturally (Drake et al., 2013).
5. Limit Screens Before Bed: Reduce blue light exposure 1-2 hours before bed to allow melatonin to do its job (Chang et al., 2015).
6. Swap Alcohol for a Calming Ritual: Try herbal tea, reading, stretching, or a warm bath to wind down without alcohol’s sleep-disrupting effects.
7. Create a Sleep-Friendly Environment: Cool, dark, and quiet rooms improve sleep. Consider things like blackout curtains, a white noise machine, breathable bedding… whatever helps you sleep best! 

Final Thoughts

It’s easy to think of alcohol as a sleep aid, but in reality, it causes more harm than good when it comes to sleep quality.

If you struggle with poor sleep, consider tracking how alcohol, caffeine, and screen time impact your rest. Even small changes, like drinking earlier, reducing blue light, or setting a bedtime routine, can lead to huge improvements in energy, mood, and focus.

Better sleep = better you.

References

Babson, K. A., Sottile, J., & Morabito, D. (2017). Cannabis, cannabinoids, and sleep: A review of the literature. Current Psychiatry Reports, 19(4), 23. https://doi.org/10.1007/s11920-017-0775-9

Brager, A. J., Ruby, C. L., Prosser, R. A., & Glass, J. D. (2021). Chronic alcohol disrupts circadian regulation of sleep and brain temperature in mice. Alcoholism: Clinical and Experimental Research, 45(1), 75-86. https://doi.org/10.1111/acer.14515

Cajochen, C., Frey, S., Anders, D., Späti, J., Bues, M., Pross, A., … & Stefani, O. (2011). Evening exposure to a light-emitting diode (LED)-backlit computer screen affects circadian physiology and cognitive performance. Journal of Applied Physiology, 110(5), 1432-1438. https://doi.org/10.1152/japplphysiol.00165.2011

Chang, A. M., Aeschbach, D., Duffy, J. F., & Czeisler, C. A. (2015). Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness. PNAS, 112(4), 1232-1237. https://doi.org/10.1073/pnas.1418490112

Drake, C., Roehrs, T., Shambroom, J., & Roth, T. (2013). Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. Journal of Clinical Sleep Medicine, 9(11), 1195-1200. https://doi.org/10.5664/jcsm.3170

Ebrahim, I. O., Shapiro, C. M., Williams, A. J., & Fenwick, P. B. C. (2013). Alcohol and sleep I: Effects on normal sleep. Alcoholism: Clinical and Experimental Research, 37(4), 539-549. https://doi.org/10.1111/acer.12006

Jaehne, A., Loessl, B., Bárkai, Z., Riemann, D., & Hornyak, M. (2009). Effects of nicotine on sleep during consumption, withdrawal, and replacement therapy. Sleep Medicine Reviews, 13(5), 363-377. https://doi.org/10.1016/j.smrv.2008.12.003