Light can interfere with the natural circadian rhythms guiding your sleep cycle. Our bodies are trained to feel alert in the presence of daylight and more relaxed after the sun goes down. If your body detects light during periods of natural nighttime darkness, this can cause you to wake up. Loud noises at night can also affect your sleep cycle by reducing the time you spend in deep sleep, which in turn may cause you to feel tired or groggy in the morning.  Some products specifically target these sleep deterrents. Options include eye masks and blackout curtains to reduce light interference, and earplugs, sleep headphones, and white noise machines to drown out loud environmental sounds.