Excerpts taken from the book, The Circadian Code, by Satchin Panda
The human body begins to get ready for the day the night before. Sleep is the beginning of our biological day, and not the end.
Every day, our body battles with lots of stressors that create cellular damage. At night, we aren't just making necessary repairs to the body; the brain is also busy consolidating memories and sending out instructions to prepare us for the next round of activity. The changes that happen at night are abolsutely critical to how we feel the next day. That's why when we are in good health and have the right amount of sleep, we wake up feeling refreshed.
We typically have between three to five cycles of REM sleep per night, occurring every 90 to 120 minutes. Adults need at least 7 consecutive hours of sleep each night. So, if you short yourself by 90 minutes or more, you lose the equivalent of one entire sleep cycle.
Between the hours of 10:00 PM and 2:00 AM, or in the first four hours after falling asleep, you get some of your best sleep. This is because these first few hours go toward paying back your sleep debt. They neutralize the urge to sleep or the tiredness you feel before going to bed. This is why it may be harder to go back to sleep if you wake up after that 4-hour period. You no longer have the sleep debt that was making you tired in the first place.
The next 3-plus hours of sleep go towards nurturing your brain and body, giving it the additional time it needs for repair and rejuvenation.
Every night adults should give themselves 8 consecutive hours of sleep opportunity, and children should have 10 hours.That includes getting into bed, settling down and the falling asleep.
Sleep debt is the difference between the amount of sleep you should be getting and the amount you actually get. So, if you slept for 6 1/2 hours last night, you're beginning your day with 30 minutes of sleep debt.
If you are shorting yourself at night, a short nap during the day is one way to repay your sleep debt.
If you continuously sleep deprive yourself, it can lead to poor performance and begins to affect our hunger and satiety hormones, like ghrelin and leptin, both of which have a circadian nature. Ghrelin is produced in the stomach whenever the stomach is empty, and it is the signal to the brain to feel hunger. Leptin is produced in fat cells and signals the brain that you are full. However, poor sleep patterns disrupt these signals and make us more prone to overeat because the brain isn't getting either of these two messages.
Eating late at night is not only bad for metabolism, it also affects sleep. This habit interferes with both falling asleep and maintaining deep sleep. In order to fall asleep, our core body temperature must cool down by almost 1 degree Fahrenheit.When we eat, our core body temperature actually goes up as blood rushes to the gut (the core) to help digest and absorbnutrients. So, eating late at night prevent us from getting into a deep sleep. To have a good night's sleep, we should have our last meal at least 2 to 4 hours before going to bed to ensure that the body is able to cool down.
Let's get to sleep:
The basic lesson for improving sleep is to increase the drive to sleep in the first place and avoid the factors that suppress or disrupt sleep. In the daytime, the drive to sleep is affected by many factors:
Length of time one has been awake: Sleep drive increases with every hour we are awake. If you want to go to bed early, you should wake up early as well.
Exercise of physical activity: Physical activity, particularly outdoor activity under the sun or under diffuse daylight, increases drive to sleep.
Timing of caffeine intake: Caffeine reduces our sleep drive and keeps us awake. Reducing caffeine after midday is a good general rule of thumb.
The best ways to wake up:
The best way to wake up refreshed is to have enough sleep by going to bed early
Get some bright light immediately after waking up. Open your curtains or turn on your overhead light. Get as close to the window as possible
Take a quick 5 to 15 minute morning walk. Do anything that will take you out of the house and into bright daylight
Try to be consistent and wake up at the same time every day. If you are waking up 2 hours later on the weekends, it is a fair sign that you are not getting restorative sleep during the week.