For some people, the slightest noise awakens them at night. For others, the wailing siren of a passing fire truck doesn’t disturb their slumber. Just why, though, remains a bit of a mystery.
Although many people are self-proclaimed light sleepers or heavy sleepers, researchers have found that little is actually known about why people react differently to noises and other stimuli during sleep.
Genetics, lifestyle choices, and undiagnosed sleep disorders may all play a role. In addition, some studies suggest that differences in brainwave activity during sleep may also make someone a light or heavy sleeper.
Light and Deep Sleep
During sleep, you alternate between cycles of REM (rapid eye movement) and NREM (non-rapid eye movement) that repeat about every 90 minutes. You spend about 75 percent of the night in NREM sleep, which consists of four stages of increasing relaxation…