- Insomnia is a sleep disorder in which there is difficulty falling or staying asleep and this can be categorized either as primary insomnia or comorbid insomnia. Comorbid insomnia is commonly associated with substance use disorders such as alcoholism.
Insomnia is defined as a complaint of disturbed sleep in the presence of an adequate opportunity and circumstance for sleep. The complaint may consist of difficulty initiating sleep, difficulty maintaining sleep, waking up too early and/or nonrestorative or poor quality sleep. For the diagnosis of an insomnia disorder to be made, the difficulty with sleep must have a negative impact on daily function.
- Alcohol is a sedative known to disrupt or promote sleep depending on the dose.
Alcohol is hypothesized to disrupt sleep through its effects on numerous pathways. Alcohol dependence causes significant changes to glutamatergic and GABAergic pathways extensively involved in the neurobiology of sleep. Alcohol dependence yields reduced melatonin levels in the early part of the night. Murine models have shown that gene-directed circadian variation influences alcohol consumption.
- For nonalcoholics, bedtime alcohol consumption may disrupt the second half of the sleep period.
Studies show that a moderate dose of alcohol consumed as much as 6 hours before bedtime can increase wakefulness during the second half of sleep. By the time this effect occurs, the dose of alcohol consumed earlier has already been eliminated from the body, suggesting a relatively long-lasting change in the body's mechanisms of sleep regulation.
- For alcoholics, sleep disturbances occur throughout the sleep period.
Sleep disturbances associated with alcoholism include increased time required to fall asleep, frequent awakenings, and a decrease in subjective sleep quality associated with daytime fatigue. Abrupt reduction of heavy drinking can trigger alcohol withdrawal syndrome, accompanied by pronounced insomnia with marked sleep fragmentation. Decreased SWS during withdrawal may reduce the amount of restful sleep. It has been suggested that increased REM may be related to the hallucinations that sometimes occur during withdrawal. In patients with severe withdrawal, sleep may consist almost entirely of brief periods of REM interrupted by numerous awakenings
- TL;DR: Alcohol in small amounts can cause sleepiness through its sedative effect in insomniacs but in large amounts can cause disruption in sleep patterns in healthy individuals.
Small amounts of alcohol can cause early sedation or sleepiness, and is often used as a sedative. However, the use of alcohol as an effective sedative can be extremely misleading because the side effects that can result are usually even more harmful and detrimental to the natural sleep cycle. For instance, due to the natural elimination of alcohol from the body, arousal and sleep fragmentation can occur and the second half of the sleep period can be drastically interrupted. This is due to the fact that, although alcohol will cause sedation, it will also decrease REM sleep in the first half of the night resulting in the rebound of REM sleep later in the night. When the rebounding of REM sleep occurs, it causes frequent awaking during the night, and suppression of REM sleep. Gene rally, with continued consumption, alcohol's sedative effects decrease and its disruptive effects remain the same or increase.
- The study mentioned by the OP in the claim is related to binge alcohol consumption and its effects on sleep-wakefulness. Binge drinking is a pattern of drinking where the drinker’s blood alcohol concentration (BAC) is 0.08 grams percent or above (i.e. for men-5 or more drinks and for women-4 or more drinks in a time period of about 2 hours). It concludes that the high BAC contributed by the binge drinking might disturb sleep regulation to cause sleep disruptions.
Contrary to this finding, it is noted that one or two alcoholic drinks may help to initiate sleep and moderate drinking is also noted to have an effect on mortality.
Substance abuse can cause chronic insomnia. This is especially true for alcohol, cocaine, and sedatives. One or two alcoholic drinks may help reduce stress and initiate sleep. However, excessive alcohol use tends to fragment sleep and cause wakefulness a few hours later. It also increases the risk for other sleep disorders, including sleep apnea and restless legs. Alcoholics often suffer insomnia during withdrawal and, in some cases, for several years during recovery.
Alcohol is known to disturb sleep in healthy people at high doses and and may be beneficial in low doses in insomniac people.
Alcohol has extensive effects on sleep and daytime sleepiness. In healthy people, acute high alcohol doses disturb sleep, whereas in insomniacs, lower doses may be beneficial. Data from healthy people suggest, however, that tolerance to alcohol’s sedative effects probably develops rapidly. This tolerance development may lead to excessive hypnotic use and, possibly, excessive daytime use for insomniacs. Sleep quality and daytime sleepiness may also relate to rates of alcohol drinking and become a gateway to excessive alcohol use.
- Substance use disorders such alcoholism is known to co-occur with insomnia.
Comorbid insomnia does not suggest that other condition(s) “cause” insomnia, but rather that insomnia and the other condition(s) co-occur, and may each warrant clinical attention and treatment.
- Evening alcohol consumption disturbs sleep in elderly persons. Alcohol is known to prevent deep and REM sleep while allowing only light sleep. Also it may contribute to impaired breathing causing further difficulty in sleeping and if taken before sleep it is found to coexist with snoring.
Although alcohol is a sedative that makes it easier to fall asleep, it prevents deep sleep and REM sleep, allowing only the lighter stages of sleep. People who drink alcohol also tend to wake up in the middle of the night when the effects of an alcoholic “nightcap” wear off.