I grew up in a Muslim religious family, and we had the first prayer of the day (Fajr) a little before sunrise, so my entire childhood, I was sleeping at 9 pm and waking up before sunrise.
As my studies became more and more demanding, I started staying up late to study more, but my wakeup time remained the same no matter what, at least while I still lived with my family.
I moved away from my family
In 2011 for the first time in my life for my studies and I think I've had the most inconsistent sleep schedule during 2011-2015.
In 2015 I moved to Turkey for my studies, of course. And that was the first time in my life when I started having a consistent sleep schedule. I didn't notice any significant effects on my physical or mental health, but I was waking up without any alarms, and I was happy with that.
In 2020 I moved to Canada
And had this brilliant idea of "living my life more" by cutting my time asleep (partly inspired by my friend who sleeps very little). So I started sleeping at 10 pm and waking up at 4:30 am sharp. Suddenly I had way more time in my day, so I was over the moon. I was doing a daily workout of 60 minutes and still be done with having breakfast and calling my family by 7:30 am.
I believed being at my desk at 7:30 am would make me way more productive, and I would be able to achieve my goals much faster. More importantly, I would be able to live my life more since I can squeeze in more entertainment hours into my day without losing work hours.
I was WRONG!
At first, I was only working from 7:30 am to 12:30 am, dedicating 1:30 pm to 3:30 pm for some specific non-PhD-research-work tasks, like managing the IEEE clubs, applying for scholarships and grants, learning about investing, learning about video editing and graphics design... The list goes on. These were still mentally exhausting tasks. After a short break, 4:00 pm to 5:00 pm was my time to practice French, do the homework, listen to music, watch TV with subtitles, anything to practice French. And 5:00 pm till bedtime was my "me time." In that, I met friends, went for walks and bike rides, visited parks, watched movies and series, painted some paintings for my apartment, and made a few DIY home decor projects.
Life was Happy and Blissful
so why did I intentionally start waking up at 10 am suddenly? If you look at my sleep history on my phone, there are a few months of non-consistent bedtime with still VERY consistent wake-up time of 4:30 am or 5 am. And after that, in the last couple of months, you'll see more consistent 1 am to 10 am sleep time. I allow myself some transition-to-sleep and transition-to-wakeup, of course, so that I still get my full 8-hour sleep.
Here's the problem
I was forcing my circadian clock to change.
But that's not the way our bodies work. Each person has a natural circadian rhythm that determines the ideal time to go to bed or wake up. Unfortunately, our school hours and office hours are not designed to suit everybody's needs.
When I analyzed my sleep patterns, I was not getting any REM sleep during my 4:30 am wake-up nights. However, when I look at my sleep analysis over more extended periods, I see that most of my REM sleep occurs right after sunrise. So waking up before sunrise meant I'm depriving myself of a vital sleep stage and the much-needed paralysis and muscle relaxation that comes with it. Did I just say paralysis? You're gonna want to read more about that in Matthew Walker's "Why we sleep: Unlocking the Power of Sleep and Dreams" but the idea is that our body needs all stages of sleep, in their respective amounts, to function properly. Poor sleep or sleep deprivation can lead to memory loss, diabetes, impaired cognitive functions, ADHD, Alzheimer's, and even cancer.
Our Circadian Rythm changes with age
Teenagers tend to have a circadian rhythm that makes them go to bed late and wake up much later than their parents. This causes frustration among parents and pushes them to "discipline" their children without realizing that they can cause lifelong severe damage to their children by forcing them to a sleep schedule not suited to the child's circadian rhythm.
So after personally analyzing my sleep stages
I decided not to force my circadian rhythm. I noticed improved sleep quality after letting myself go to sleep late and wake up late. Not to say that sleeping late and waking up late is "good." On the contrary, what I want to emphasize is:
There is no universal good or bad bed-time and wakeup-time.
Each individual is different, and so is their circadian rhythm. Age can be a big factor in determining one's most probable circadian rhythm, but there are no guarantees. You have to analyze your sleep patterns and monitor your sleep quality over time to see the best sleep and wakeup-time for you.
The Gadget that I Recommend
based on my personal experience so far, Fitbit Charge 4 if you are looking for a budget option and don't want to pay for third-party apps for sleep tracking. If you already own an Apple watch, you can use third-party apps such as pillow to track your sleep.
Personally, for me, what I want to try next for sleep tracking is Oura ring for sleep tracking since I am also trying to minimize the LED lights around me at night. Apple watch is quite good at keeping the watch face entirely off during the night unless you specifically want to see time but sometimes, when you're wearing the watch too loose, the sensor lights on the back can disrupt your sleep.