A little booze before bedtime might help you fall asleep faster. But various studies show that alcohol is anathema for restorative sleep. A new review paper describes just how detrimental a few drinks can be.

The researchers pored over 20 studies conducted in controlled lab settings. They found a clear trend that just about any amount of alcohol alters sleep. And the effects are usually bigger with more drinks.Just two drinks or more cut REM sleep, which is important for memory and health. And those deep, slow-wave sleep periods are also reduced for people who have tied on more than one

.Perhaps the most potent finding is that just a single dose of alcohol in the late evening can zap the efficacy of your z's. The paper is in the journal Alcoholism: Clinical and Experimental Research. [Irshaad Ebrahim, et al., Alcohol and Sleep I: Effects on Normal Sleep]Disrupted and insufficient sleep has been linked to everything from weight gain to heart problems. Not to mention harming memory and well-being. It may be time to say goodnight to the nightcap.