Subjects
Biology
Chemistry
AP Chemistry
English
AP English Literature
Psychology
Nov 20, 2025
633
2 pages
Your body runs on several different biological clocks that control everything from when you feel sleepy to when... Show more
Infradian rhythms are biological cycles that last longer than 24 hours - think monthly or seasonal patterns that your body follows naturally. The most well-known example is the menstrual cycle, which runs roughly every 28 days from the start of one period to the day before the next.
What's fascinating is that whilst the menstrual cycle is controlled internally (endogenous), it can actually be influenced by external factors like other women's cycles. This menstrual synchrony might have evolutionary benefits - our ancestors who menstruated together could help care for each other's babies, improving survival rates.
Seasonal Affective Disorder (SAD) is another infradian rhythm that affects many people during winter months. When daylight hours shrink, some people develop depression because their internal clocks get disrupted by the prolonged darkness. The good news? Light therapy boxes can help reset your body clock, though they might cause headaches or eye strain.
Quick Tip If you feel more depressed during winter months, you're not imagining it - it's a real biological rhythm that affects millions of people!
Ultradian rhythms are shorter than 24 hours, and the most important one happens whilst you're sleeping. Your brain cycles through five stages of sleep approximately every 90 minutes throughout the night, each with distinct brainwave patterns.
Stages 1 and 2 involve light sleep with high-frequency, short waves - this is when you might wake up easily. Stages 3 and 4 are deep sleep, characterised by slow, powerful brainwaves that help your body recover. Stage 5 is REM sleep (Rapid Eye Movement), where your body becomes paralysed but your brain acts like it's awake - this is when most vivid dreams occur.
Understanding these sleep stages has revealed why older people often struggle with sleep quality. Deep sleep stages (3 and 4) naturally decrease with age, explaining why your grandparents might wake up more frequently than you do.
Research shows massive individual differences in sleep patterns, making it difficult to define "normal sleep". Whilst sleep labs help scientists control variables, people attached to monitoring equipment rarely sleep as naturally as they would at home.
Remember Your sleep cycles repeat every 90 minutes - that's why you sometimes wake up naturally feeling refreshed whilst other times you feel groggy, depending on which stage you're in!
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
You can download the app in the Google Play Store and in the Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
15
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Includes information about the consciousness of the mind, sleep, REM, hypnosis, drug categories, etc.
PsychologyStudy guide on chapter 3, including information on sleep and substances. Information was from the textbook Introduction to Psychology by Hawkes Learning and supplemented by my professor's resources.
PsychologyStudy notes covering AP Psych curriculum
AP PsychologyExplore the intricate relationship between brain structures and their functions in this comprehensive overview of biopsychology. This study note covers key concepts such as sleep cycles, REM and non-REM sleep, neuroplasticity, and the biological bases of behavior. Ideal for students studying cognitive neuroscience, this resource provides insights into the cerebral cortex, central and peripheral nervous systems, and the role of neuroimaging techniques like EEG. Enhance your understanding of how biological processes influence behavior and cognition.
PsychologyIn class notes
AP PsychologyAP Psych
AP PsychologyApp Store
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
Your body runs on several different biological clocks that control everything from when you feel sleepy to when you're most alert. These rhythms, which last longer or shorter than 24 hours, play a massive role in your daily life and... Show more
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Infradian rhythms are biological cycles that last longer than 24 hours - think monthly or seasonal patterns that your body follows naturally. The most well-known example is the menstrual cycle, which runs roughly every 28 days from the start of one period to the day before the next.
What's fascinating is that whilst the menstrual cycle is controlled internally (endogenous), it can actually be influenced by external factors like other women's cycles. This menstrual synchrony might have evolutionary benefits - our ancestors who menstruated together could help care for each other's babies, improving survival rates.
Seasonal Affective Disorder (SAD) is another infradian rhythm that affects many people during winter months. When daylight hours shrink, some people develop depression because their internal clocks get disrupted by the prolonged darkness. The good news? Light therapy boxes can help reset your body clock, though they might cause headaches or eye strain.
Quick Tip: If you feel more depressed during winter months, you're not imagining it - it's a real biological rhythm that affects millions of people!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Ultradian rhythms are shorter than 24 hours, and the most important one happens whilst you're sleeping. Your brain cycles through five stages of sleep approximately every 90 minutes throughout the night, each with distinct brainwave patterns.
Stages 1 and 2 involve light sleep with high-frequency, short waves - this is when you might wake up easily. Stages 3 and 4 are deep sleep, characterised by slow, powerful brainwaves that help your body recover. Stage 5 is REM sleep (Rapid Eye Movement), where your body becomes paralysed but your brain acts like it's awake - this is when most vivid dreams occur.
Understanding these sleep stages has revealed why older people often struggle with sleep quality. Deep sleep stages (3 and 4) naturally decrease with age, explaining why your grandparents might wake up more frequently than you do.
Research shows massive individual differences in sleep patterns, making it difficult to define "normal sleep". Whilst sleep labs help scientists control variables, people attached to monitoring equipment rarely sleep as naturally as they would at home.
Remember: Your sleep cycles repeat every 90 minutes - that's why you sometimes wake up naturally feeling refreshed whilst other times you feel groggy, depending on which stage you're in!
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
You can download the app in the Google Play Store and in the Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
15
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Includes information about the consciousness of the mind, sleep, REM, hypnosis, drug categories, etc.
PsychologyStudy guide on chapter 3, including information on sleep and substances. Information was from the textbook Introduction to Psychology by Hawkes Learning and supplemented by my professor's resources.
PsychologyStudy notes covering AP Psych curriculum
AP PsychologyExplore the intricate relationship between brain structures and their functions in this comprehensive overview of biopsychology. This study note covers key concepts such as sleep cycles, REM and non-REM sleep, neuroplasticity, and the biological bases of behavior. Ideal for students studying cognitive neuroscience, this resource provides insights into the cerebral cortex, central and peripheral nervous systems, and the role of neuroimaging techniques like EEG. Enhance your understanding of how biological processes influence behavior and cognition.
PsychologyIn class notes
AP PsychologyAP Psych
AP PsychologyApp Store
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
