I used to dread Q&A after presentations. What if I didn’t know the answer? What if I sounded stupid?
Then I realized that getting asked questions that I don’t know the answer to is the key to my learning.
And, surprise, people seem to have more trust in what I say when I admit when I don’t know.
I now look forward to being stumped.
I kicked off a three-part speaker series at Sonoma’s Vintage House a couple of weeks ago and left with two great questions I didn’t know the answer to. Yay!
I hope to make these “Good Question” posts a regular format as I do more speaking events and get more good questions.
Do you have a question? Please feel free to leave it in the comments below, and I may use it as inspiration for my next deep dive or post. Thanks for keeping me on my toes.
Good Question #1: How are REM and non-REM (NREM) sleep distributed throughout the night?
My answer: Both REM and NREM sleep are important. During REM, the brain consolidates memories, processes emotions, and promotes learning, creativity, and problem-solving. NREM, on the other hand, is the time for physical renewal, repair, and supporting the immune system.
But how much of each does one need? While I know that most people need 7.5-9 hours of sleep, I had no idea how that time was divided between REM and NREM sleep.
What I found out: According to my go-to sleep expert, Dr. Matt Walker, the brain transitions through REM and NREM sleep every 90-110 minutes. Over a standard 7.5-9 hours of sleep, most adult brains spend about 25% of the time in REM and 75% in various stages of NREM sleep.
But the time spent in each stage shifts throughout the night. The first half of the night favors NREM sleep, especially the deepest stages of NREM (stages 3 & 4). I can attest to this as I typically sleep soundly until 1 am and hardly anything can wake me up during this time. If I have to stay up late or get woken up during my NREM stages? I certainly don’t feel like I’ve gotten deep, restorative sleep.
During the second half of the night, more REM sleep occurs. This is the time of dreams. Have you ever woken up in the early hours of the morning with the sensation of your dream in reach? This is REM sleep. And according to my mom, if you tell someone about your dreams before breakfast, they will come true (not evidence-based, but don’t tell her!).
Check out this TED talk by Dr. Matt Walker himself for a great explanation of the different stages of sleep:
Good Question #2: What is adenosine, anyway?
My answer: This question came up as I was describing the biological mechanisms of sleep and how caffeine can work for — and against — us.
Most people are aware of melatonin, the light-sensitive hormone that initiates sleep. Yes, you read that right. Melatonin doesn’t keep you asleep; its role is to help you fall asleep (more on that in the future).
A lesser-known sleep concept is the idea of “sleep pressure.” This is a phenomenon in which something called adenosine builds up in the brain while awake.
The more adenosine that builds up, the more tired you feel. Adequate sleep helps clear adenosine and contributes to the feeling of being refreshed when you wake up.
But what is adenosine? I’d never actually thought about it. But I’m glad I was asked because it gave me the chance to nerd out and learn some cool stuff.
What I found out:
Throughout the day, the energy that your brain uses is obtained from ATP (adenosine triphosphate = adenosine + 3 phosphate groups). Oh, hello, college biochem!
Energy is released as the bonds between the phosphate groups and the adenosine backbone are broken.
The adenosine backbone is known as a nucleoside, which consists of adenine (nitrogen base) and ribose (a five-carbon sugar).
The more ATP that is used for energy, the more adenosine that builds up.
Once you fall asleep, adenosine is gradually cleared away or converted back into ATP, leaving you feeling awake and refreshed after a good night’s sleep.
(Side note: Caffeine blocks adenosine receptors, so you don’t feel the fatiguing effects of the buildup of adenosine. Caffeine does not give you energy. It just tricks your body into feeling less tired.)
There you have it! Thank you for the great questions. Please keep them coming.
Thanks for being here,
~Allison