Not surprisingly, on the nights they drank alcohol, people showed more slow wave sleep patterns, and more so-called delta activity—a process linked to the restorative aspects of deeper sleep, when memories are firmed up, the brain’s detritus is cleared out and hard-working neurons get some much-needed replenishment.
But that wasn’t the only thing going on in their brains. At the same time, alpha wave patterns were also heightened, which doesn’t happen during normal sleep. Alpha activity tends to occur when the brain is awake but quietly resting, in metabolic break mode. Having both delta and alpha activity together therefore leads to disrupted sleep, since the alpha functions tend to offset any restorative efforts the brain neurons are trying to squeeze in.