Written by Lisa Meltzer, the Sleep Science Advisor at Zepp Aura
Just like your doctor tells you to eat five fruits and vegetables a day, and your dentist tells you to brush and floss twice a day, sleep providers will tell you to go to bed and wake up at the same time every day.
While it may be hard to keep a consistent routine, and it is tempting to stay up late and sleep in on weekends, here is some information about why that consistent schedule is so important.
The Big Two of Sleep
There are two main things that help us sleep at night and stay awake during the day. The first is sleep pressure, or the need to sleep. The second is our circadian rhythm or internal clock.
Homeostatic Sleep Pressure
Homeostasis is a balance. We all like to be balanced in life. For example, we don’t like to be too hungry or too full. The same is true for sleep, where we stay balanced through most of the day.
If you have had a full night of sleep, you should wake up in the morning without sleep pressure, or the feeling that you need more sleep. As the day goes on, sleep pressure begins to build. Every hour that you are awake you will be sleepier than the hour before. After a certain point (typically around 16 hours for adults), you will have enough sleep pressure to fall asleep. During the night your sleep pressure is relieved by sleep.
- Since it can also be hard to turn off your brain in the “dark hours,” consider using the Zepp Aura or other relaxation strategies to help you return to sleep.
Circadian Rhythm/Internal Clock
Most people notice their internal clock when they travel across time zones, or when daylight saving time starts or ends. Then you have to get your body clock to match your watch or wall clock.
Fun fact — our internal clock runs on a day that is a little more than 24 hours. So every day we have to reset our internal clock with external cues around us. These external cues are called Zeitgebers or time givers, and include meals and routines, with light and dark the strongest cues for our internal clock.
When our eyes see darkness in the early evening, this cues our brain to make melatonin. Melatonin is a naturally produced hormone that helps prepare our bodies for sleep. During the night, melatonin continues to be released to help us stay asleep while our sleep pressure wears off. In the morning, when we see bright light, this cues our brain to stop making melatonin and wake up, resetting our internal clock.
- To help keep your internal clock on schedule, dim all bright lights after dinner, using only small lamps. In the morning, get lots of natural bright sunlight exposure.
Social Jetlag
So what happens if we stay up late or sleep in, especially on weekends? We end up with social jetlag, which is similar to traveling across time zones, but without the fun activities at your destination.
Let’s use Mark as an example. Mark has a weekday bedtime of 11:00 pm and a weekday wake time of 7:00 am. But on both Friday and Saturday nights, Mark stays up socializing or watching movies until 2:00 am and sleeps in until 10:00 am. On Sunday night, Mark has a hard time falling asleep at 11:00 pm. Why?
First, Mark made his day longer by staying awake until 2:00 am, shifting his internal clock. It is easy to make our days longer (which is why it is easier to travel west or to go off daylight saving time). We can use caffeine to help us stay awake, or engage in fun activities to keep us alert. For most people it only takes a couple of days to get on this new schedule.
But by going to bed at 11:00 pm on Sunday night, Mark made his day much shorter (like traveling east or the start of daylight saving time). So his internal clock is not in the right time zone, and he is not tired at bedtime. It can take up to 5 days to adjust the internal clock this direction.
- For optimal sleep health, try not to shift your bedtime and wake time by more than one hour.
Bottom Line
While challenging, maintaining a consistent bedtime and wake time every night is one of the most important keys for optimal sleep health.
