No two people have the same sleep cycles, and nobody has the same cycle twice.

Many factors can influence sleep cycles, including diet, exercise, medications, drugs or alcohol, stress, sleep disorders, and sleep deprivation.

Age and gender can play a role, too: women tend to sleep more soundly than men, and as we age, we sleep more restlessly.

A typical sleep cycle has five stages and takes 90-110 minutes. During Stage 1 of your sleep cycle, you sleep lightly. At Stage 2, your sleep gets progressively deeper.

At Stages 3 and 4, also known as "Delta Sleep," you sleep most heavily; this is when your body rebuilds itself.

Stage 5 of sleep, also known as REM (rapid eye movement) sleep, is marked by extensive physiological changes, such as accelerated respiration, increased brain activity, rapid eye movement, and muscle relaxation. People dream during REM sleep.

In the first third of the night, Delta sleep stages last longer than REM stages. As the night progresses, Delta sleep diminishes in length. By the last third of the night, Delta sleep usually ceases, while REM stages lengthen.

SLEEPTRACKER® may find multiple almost-awake moments within the sleep cycle. Almost-awake moments may also vary in frequency throughout the night.

By monitoring your sleep cycles for optimal waking moments during the preset ALARM WINDOW, SLEEPTRACKER® finds those almost awake-moments and gently wakes you when you're most alert. The result? You wake up refreshed instead of groggy. Waking up has never been easier.