Futurehead.com

In this clamorous modern world, heavy sleepers have an advantage: They can snooze despite noisy neighbors and car alarms, and they’re capable of conking out on a red-eye flight to awake refreshed and smiling.

But how do these sound sleepers do it? According to a neuroscience study published today in Current Biology, they’re blessed with a type of brain activity that may essentially block out noise.

Sleep researchers from Harvard Medical School performed a slightly torturous experiment on 12 healthy volunteers. On their first night at the sleep lab, the subjects’ brain waves were monitored via electroencephalography (EEG), but they were otherwise left in peace. That night, the researchers measured one particular sleep phenomenon: the brief bursts of high-frequency waves known as “sleep spindles.” On the following two nights, the researchers did their best to replicate a really irritating night’s sleep.