How and why alcohol affects your sleep

Alcohol has a complex, two phase effect on sleep, initially inducing drowsiness but later disrupting sleep patterns and reducing overall sleep quality.

Alcohol’s initial sedative effect is due to its ability to increase the activity of a chemical in the brain called GABA. GABA is an inhibitory neurotransmitter that plays a crucial role in regulating brain activity and promoting relaxation. When alcohol binds to GABA receptors, it enhances GABA’s inhibitory effects, leading to decreased brain activity and a sense of drowsiness. This initial sedative effect is responsible for the ease in falling asleep after consuming alcohol.

As the body metabolises alcohol, its sedative effects gradually diminish. This decline in GABA inhibition allows other chemical neurotransmitters, such as glutamate, to become more active. Glutamate is an excitatory neurotransmitter that plays a role in arousal and wakefulness. Increased glutamate activity contributes to sleep fragmentation and frequent awakenings and reduces the amount of time in REM sleep, a crucial stage for dreaming and cognitive function.  This reduction in REM sleep can leave one feeling unrested and unrefreshed upon waking and the overall reduced sleep quality produces daytime fatigue, irritability, and impaired cognitive function.

Additional Factors

Apart from the GABA-glutamate balance, other physiological factors contribute to alcohol’s disruptive effects on sleep:

  • Reduced adenosine: Adenosine is a neurotransmitter that promotes sleepiness and accumulates in the brain as we stay awake. Alcohol interferes with adenosine’s actions, reducing the drive for sleep and contributing to wakefulness as alcohol’s sedative effect wears off.
  • Altered hormone levels: Alcohol can disrupt the production of hormones that regulate sleep, such as melatonin and cortisol. These hormonal imbalances can also contribute to sleep disturbances.
  • Diuretic effect: Alcohol is a diuretic, meaning it increases urine production. This can lead to dehydration and frequent urination during the night, further disrupting sleep.
  • Temperature regulation: Alcohol can cause an increase in body temperature, leading to night sweats and discomfort during sleep.

Factors Affecting Alcohol’s Impact on Sleep

The extent to which alcohol affects sleep can vary depending on several factors.  Some individuals are more sensitive to alcohol’s effects than others but in practice, the more alcohol consumed, the more this leads to greater sleep disruption, and drinking close to bedtime can have a more pronounced effect on sleep.  It’s also the case that the more regular the alcohol consumption then the more persistent will be the sleep disturbances.


Long-Term Effects:

  • Chronic alcohol use is associated with an increased risk of developing sleep disorders like insomnia.
  • Alcohol relaxes the muscles, including those in the throat, which can worsen sleep apnea in those predisposed as it further relaxes the muscles controlling the upper airway making it more prone to collapse during sleep. This amplifies reductions in oxygen.
  • Long-term use can disrupt the normal sleep cycle. While occasional light drinking shows little effect, consistent heavy alcohol consumption can significantly disrupt the sleep architecture affecting the proportion of time spent in each sleep stage. It may perpetuate insomnia and sleep deficits creating a troublesome cycle long-term.

Managing Alcohol’s Impact on Sleep

To minimise the negative effects of alcohol on sleep, consider these tips:

  • If you choose to consume alcohol, do so in moderation. Avoid excessive alcohol consumption, especially close to bedtime.
  • Opt for non-alcoholic beverages at social gatherings.
  • Counteract the dehydrating effects of alcohol by drinking water before bed.
  • If you’re experiencing persistent sleep issues related to alcohol, consider seeking advice from a healthcare professional or sleep specialist.

Read our article tips for reducing alcohol intake for more ideas on reducing drinking.

In summary, alcohol may hasten sleep onset due to sedation initially but it reduces overall sleep quality and the continuity necessary for proper biological functioning, healing, and restoration overnight.  Prioritising good sleep hygiene and considering the effects of alcohol on sleep can contribute to better overall sleep health.