What is normal sleep?
Good sleepers close their eyes, fall asleep quickly and wake up in the morning feeling refreshed. It should be that easy.
When you have insomnia, sleep isn’t easy. You can’t fall asleep. Or you lie awake for hours in the middle of the night, exhausted but wired.
Whether you’ve been suffering for years or even decades, understanding how sleep works is the first step to snoozing great again.
There are two body systems that hard-wire you for sleep.
The first is your biological circadian clock.
Your body clock, or circadian rhythm, gets its cues from light and food. When the sun sets, your body starts to produce a hormone called melatonin. This hormone has a relaxing effect, which helps you feel sleepy and ready for bed at night. However, if you surround yourself with bright artificial lights and blue light from screens, your body will still think it’s daytime and it won’t prepare for sleep.
In the early morning hours, your body begins to release a stress hormone called cortisol. This hormone helps you wake up and gives you energy throughout the day. Your circadian rhythm doesn’t stay steady all day; instead, it peaks and dips. The natural drop that happens in the early afternoon explains why you may feel tired after lunch and why so many cultures take a nap at that time.
The second system that regulates sleep is your sleep/wake homeostasis, your internal counter or timer that’s responsible for your sleep drive. The longer you are awake, the stronger the drive for sleep becomes as the hormone adenosine builds up in your body. Eventually, you feel as though you can fight it no longer and you need to sleep. During sleep, this need dissipates, so when you wake up you don’t feel the need to sleep anymore if you slept well.
Imagine you’re wearing a backpack, representing your sleep drive. As the day wears on, you collect a brick for every two hours you are awake. When you go to bed at night, you’re tired because you have a very heavy backpack. If you get the sleep you need, you wake up with an empty backpack.
I’ve worked with a few clients who don’t feel sleepy anymore even though they feel tired. This can happen when your gut isn’t healthy enough to make adenosine. If you don’t feel sleepy at night, your gut isn’t healthy.
This leads to the concept of “sleep debt.” Sleep debt is the amount of sleep your body needs minus the amount of sleep you actually get.
Amount of sleep you need the amount of sleep you get=sleep debt
If your body needs 8 hours of sleep and you sleep 6 hours, you have 2 hours of sleep debt the next morning. You have 2 bricks in your backpack. That missed sleep doesn’t disappear. Instead, it accumulates every day. If you sleep 6 hours a night Mon-Fri, you have 10 hours of sleep debt that’s impossible to make up over the weekend. If you continuously accumulate sleep debt, certain systems in your body will start breaking down. Or you’ll get sick and your body will force you to rest.
Stages of sleep
Knowing the stages of sleep will help you understand if your sleep patterns are normal or not. You experience two stages of sleep: REM and 3 stages of non-REM sleep.
Stage 1 non-REM: The first stage of sleep is the transition between being awake and asleep. During these few minutes of light sleep, your body temperature drops, your breathing slows and your heart rate decreases. You may not even think you’re sleeping even though your brain waves would indicate that you are. Every once in a while this is when my husband nudges me and tells me I’m snoring, and I tell him that I wasn’t even asleep yet!
Stage 2 non-REM: The first true stage of sleep continues to be light sleep before you fall into a deep sleep. If someone woke you up during this stage, there is a 50% chance you would tell them you weren’t even sleeping yet. In fact, insomniacs often think they are awake when they are in this second stage of sleep.
Stage 3 non-REM: The third stage of sleep involves slow-wave or deep sleep. This is the most restorative stage when your body repairs itself and your brain stores memories and information from the day. You spend more time in this stage at the beginning of the night which is why most people say they sleep “better” the first part of the night.
REM sleep: Finally you enter REM (rapid eye movement) sleep, also called the “dream stage” because most of your dreams happen in this state. Your brain is extremely active during this stage, processing emotions and connecting information that was consolidated during deep sleep. Most REM sleep happens the last half of the night, which is why you feel like you sleep more restlessly toward morning and why you tend to wake up remembering your dreams.
Adults cycle through these sleep stages about every 90 minutes. Technically no one sleeps through the night since you partially wake up as you transition from one sleep cycle to the next. You may or may not remember these partial awakenings but this is when you change positions or get up to go to the bathroom.
Now you know why it's normal:
-to feel tired after lunch
-to take a few nights to make up for missed sleep
-to misjudge how long you sleep
-to feel like you sleep better the first half of the night and more restlessly toward morning
-to wake up briefly throughout the night
How do you know if you slept well? You can use a tracker but many of my clients get more anxious and worried when they track their sleep. The best way to tell if you slept well is that you wake up feeling rested and full of energy!