Fix the sleep, and the drinking may follow. That's the bet behind a new analysis in Drug and Alcohol Dependence. Researchers gave heavy drinkers with insomnia an online sleep program and tracked their drinking for six months. Drinking went down. In women it went down further than in men.

I've written before about how a bad night before drinking raises blackout risk, even at the same dose. That study looked at one night. This one asks a bigger question: if you treat the insomnia itself, does the drinking change too?

There was already a reason to expect a sex difference. Earlier research suggests poor sleep and problem drinking are more tightly linked in women. But according to the authors, nobody had checked whether insomnia treatment changes drinking differently for men and women.

What they did

The team pooled data from two clinical trials. To be included, people had to meet three criteria:

  • at least one binge per week (4+ drinks in one sitting for women, 5+ for men)
  • an AUDIT (Alcohol Use Disorders Identification Test) score above 7, which points to risky drinking
  • an ISI (Insomnia Severity Index) score above 14, which means real insomnia, not the odd restless night

That left 184 people. Researchers randomly assigned 102 of them to SHUTi (Sleep Healthy Using the Internet), a digital version of cognitive behavioral therapy for insomnia. The other 82 got an active control program, so both groups had something to do for the nine weeks.

Participants reported their own sleep and drinking four times: at the start, right after the nine weeks, then at three and six months. The drinking measures that matter here are how many days people drank at all, and how many of those were heavy drinking days.

What they found

Over time, SHUTi worked better in women than in men on every main outcome:

  • Sleep. Women's sleep improved more.
  • Drinking days. Women cut the total number of days they drank by more.
  • Heavy days. Women also cut more heavy drinking days.

All three sex differences were statistically significant (p ≤ 0.038).

The effect sizes make the gap clearer. Researchers compared how much each group changed from its own starting point, using Cohen's d (a standard measure of how big a change is). For women on SHUTi, the drop in drinking ranged from 0.92 to 2.23. For men on SHUTi, from 0.65 to 1.95.

Don't skip past the men's numbers. A d of 0.65 to 1.95 is still a substantial change. SHUTi didn't fail in men. It helped both sexes, and women more.

What it means

What interests me most is the direction of the effect. The program never told anyone to drink less. It targeted sleep, and drinking days fell anyway. That fits the idea that for some people alcohol partly works as a sleep aid, a bad one. Once falling asleep gets easier, the nightly drink has less of a job.

Why the gap between women and men? The paper doesn't say. It records the difference and stops. I could guess, but this data can't settle it, and I'd rather not invent a mechanism. One sex-differences finding I do keep in mind is a brain pathway tied to binge drinking that runs in opposite directions for men and women. Separate study, separate question. Still, it's another sign that "heavy drinker" doesn't describe one kind of person.

I wouldn't take this too far, for three reasons. Every number is self-reported: no sleep trackers, no alcohol biomarkers. The sample combines two separate trials, which can blur differences between their protocols. And follow-up ends at six months, so we don't know if the change lasts.

What I take from it in practice: sleep and drinking feed each other both ways. Late drinks make for worse nights. A worse night lowers your tolerance the next evening and makes the next drink more tempting. Much of that loop runs on timing you never see. The last glass feels like a wind-down, but the alcohol is still in your system when you lie down. AlcoBalance shows you in the moment when your level will actually fade, and lets you set that against when you plan to sleep and what tomorrow needs from you. Then stopping now or having one more is a conscious choice, made while you're still steering the evening and not left for the morning to deal with.

One caveat. This study looked at people with real insomnia and a pattern of heavy drinking, so the size of the effect may not carry over to someone who just sleeps badly after a wedding. But the direction is hard to ignore: when the sleep side changed, the drinking side changed with it. In this trial, more so for women.

Source: Drug and Alcohol Dependence, DOI