during sleep. This "clock" in the brain runs on a 24-hour cycle with the result that we feel most sleepy around 2:00-4:00 am and in the afternoon between 1:00-3:00 pm. We need to have continuous sleep that becomes restorative and results in feeling refreshed and alert for the day ahead.
Quality of Sleep – Poor Sleep has Consequences
Quality sleep also means that it is continuous and uninterrupted. As we get older, sleep can be disrupted due to pain or discomfort, the need to go to the bathroom, medical problems, medications, and sleep disorders as well as poor or irregular sleep schedules. Establishing a regular bed and wake schedule and achieving continuous sleep helps you sleep in accordance with your internal biological circadian clock and experience all of the sleep stages necessary to reap the restorative, energizing and revitalizing benefits of sleep.
States and Stages of Sleep
As we sleep, we pass through different states and stages of sleep – more likely to be experienced with continuous sleep. This "sleep architecture" follows a predictable pattern of REM (rapid-eye movement) and NREM (Non-Rapid Eye Movement) sleep throughout a typical 8-hour period. Each of these states alternates every 90 minutes.
Both states are important to experiencing quality sleep. Again, getting the right mix and enough of both REM and NREM sleep will help you maintain your natural sleep architecture and have restful and restorative sleep.
*Time spent in these states and stages of sleep varies by age.
NREM: 75% of night*
As we begin to fall asleep, we enter NREM, which is composed of Stages 1-4.
Light sleep; between being awake and entering sleep
Onset of sleep; becoming disengaged with the environment; breathing and heart rate are regular and body temperature goes down
Stage 3 & 4
Deepest and most restorative sleep; blood pressure drops; breathing slower; energy regained; and hormones are released for growth and development
REM: 25% of night
First occurs about 90 minutes after falling asleep and increases over later part of night; necessary for providing energy to brain and body; brain is active