Tsukuba, Japan—During deep sleep, brain wave amplitude increases, and "δ (delta) power," a key objective indicator of sleep quality, is observed; higher delta power corresponds to deeper, more ...

Lindsey Ellefson is Lifehacker’s Features Editor. She currently covers study and productivity hacks, as well as household and digital decluttering, and oversees the freelancers on the sex and ...

So why do so many of us still try to multitask? We’re too busy with too much to do and too little time to do it in. The temptation to accomplish multiple things at the same time is practically ...