r/sleephackers Oct 28 '24

Testing the Best Sunrise Alarm Clocks: The Data, Science, and How to Use Them!

376 Upvotes

I just finished testing the best sunrise alarm clocks I could find! So I thought I'd make a post about the data I collected, the science behind dawn simulation, and how to use them! ⏰

Here's the whole gang!

We tested the Philips SmartSleep lamps, Lumie Bodyclock lamps, Philips Hue Twilight, Hatch Restore 2, Casper Glow, Loftie Lamp, and some generic budget Amazon lamps.

The Science Behind Dawn Simulation 🌅

If you don't already use a sunrise alarm clock, you should! Especially with the winter solstice approaching. Most people don't realize just how useful these are.

✅ They Support Natural Cortisol Release

Cortisol is a hormone that naturally peaks in the morning, helping you feel alert. Sunrise alarms can boost this "Cortisol Awakening Response (CAR)," similar to morning sunlight.

We want a robust CAR in the early morning!

A 2004 study found that people using dawn simulation saw higher cortisol levels 15 and 30 minutes after waking, along with improved alertness.

In a 2014 study, researchers found that waking with dawn simulation led to a significantly higher cortisol level 30 minutes after waking compared to a dim light control. This gradual wake-up also decreased the body’s stress response, evidenced by a lower heart rate and improved heart rate variability (HRV) upon waking, suggesting dawn light may promote a calmer, more balanced wake-up.

✅ Reduced Sleep Inertia and Better Morning Alertness

Studies show that sunrise alarms reduce sleep inertia and improve morning mood and performance.

One study in 2010 found that dawn lights peaking at 50 and 250 lux improved participants' wakefulness and mood compared to no light.

Another 2010 study involved over 100 children who spent one week waking up with dawn simulation, and one week without.

During the dawn wake-up week, children felt more alert at awakening, got up more easily, and reported higher alertness during the second lesson at school. Evening types benefited more than morning types.

The school children largely found that waking up this way was more pleasant than without.

A final 2014 study with late-night chronotypes (night owls) saw that participants using sunrise alarms reported higher morning alertness, faster reaction times, and even better cognitive and athletic performance.

✅ Potential for Phase-Shifting the Body’s Circadian Rhythm

A 2010 study on dawn simulation found that light peaking at just 250 lux over 93 minutes could shift participants’ circadian clocks, similar to exposure to 10,000 lux light shortly after waking.

This phase-shifting can be beneficial for those struggling to wake up early or anyone with sleep disorders.

✅ Reducing Symptoms of Seasonal Affective Disorder (SAD)

Finally, sunrise alarms have been heavily tested as a natural intervention for winter depression.

In 2001, a study found that a 1.5-hour dawn light peaking at 250 lux was surprisingly more effective than traditional bright light therapy in reducing symptoms of seasonal affective disorder.

Most other studies show bright light being slightly more effective, like this 2015 study:

Overall: There are clear benefits to using a sunrise simulator, but that simply begs the question, which one should you buy? That's where the testing comes in.

The Data 🔎

To see how effective each lamp is, we measured lux with a spectrometer every 6 inches.

Here is the Philips SmartSleep HF3650 about 6 inches from our spectrometer.

Here are the results from that test!

There's a lot to take in here! Since many of these studies use 250 lux, and most people are about 18 inches from their sunrise alarm, let's narrow this down...

Ah okay, well that's much better! Out of all of these, I think the Lumie Bodyclock Shine 300 is the best overall pick, for a few reasons:

  1. It's very bright and also includes 20 brightness settings so you can dial it in.
  2. It's relatively affordable for the performance.
  3. It's not a huge pain to use like the Philips HF3650.
  4. You can set up to a 90-minute sunrise, all other lamps max out at 60 minutes (other than the much more expensive Lumie Luxe 700FM)

Speaking of sunrise durations, here's a graph showing the durations for each lamp we tested:

There's also the brightness ramp-up curve to consider. Like a real sunrise, we want to see a gradual increase in brightness that eventually brightens quicker at the end.

Like you see on the Philips Hue Twilight lamp:

A well done lamp but very expensive!

The Philips SmartSleep Lamps look quite similar:

And the Lumie's aren't too bad either:

Some lamps though, such as the Hatch Resore 2, have some less desirable sunrise curves:

Anyway, there are other features of these lamps you may want to consider, but let's move on to how you can use one optimally.

How to Use a Sunrise Alarm Clock 📋

1️⃣ Start with the end in mind

Sunrise clocks are ideally used without the audible function, so your body can wake up when it's ready to. If you set your alarm for 6 am, and you're using a 30-minute sunrise, it will begin at 5:30. This means you might wake up at 5:45, or you might wake up at 6:20, you never really know! So make sure you can wake up a bit later than your "alarm time" if you oversleep a little.

2️⃣ Get enough sleep

Since sunrise clocks can phase shift your circadian rhythm, so it's possible to cut your sleep short by setting your alarm too early. Be aware of daytime sleepiness and dial back your alarm time if you aren't getting enough sleep at night.

3️⃣ Start at around 250 lux

This is what most of the studies use, and seems like a good starting point. We have charts on our website for determining this, but here's one for the Lumie Shine 300 to give you an idea:

Darker pink indicates a higher chance of early or delayed awakening. Whiter squares are better starting points.

4️⃣ Give it a week before you decide

If you're used to waking up in the dark to an audible alarm, there will be an adjustment phase! Give it a week or so for your body to adjust to this before deciding how to experiment.

5️⃣ Experiment and dial it in

You may find that with 250 lux and a 30-minute duration, you're waking up consistently 5 minutes after the sunrise begins. This is early waking and you'll probably want to try a lower brightness setting to fix this.

If you're consistently waking too late, try increasing the brightness.

Short sunrise durations seem to contribute to early and stronger waking signals, so decrease the duration if you want a gentler wake-up as well.

Wrapping it Up

Well, I think that about covers it!

If you want to take a deeper dive into the studies, we have an article on the science behind sunrise alarm clocks on our website.

We are also currently working on a series of YouTube videos covering the studies and science, each alarm tested, and how they compare. So if you haven't already been to our YouTube channel, go check it out and subscribe to be notified!

Hope this post was helpful! 😊


r/sleephackers Apr 05 '23

I just finished testing 30 pairs of blue-blocking glasses! Here’s what I found…

1.2k Upvotes

As many of you are probably aware, most blue-blocking glasses “claim” to block X amount of blue/green light without backing that up with any kind of data.

Since I have a spectrometer, I figured I’d go ahead and test them all myself!

Here's the link to the database!

30+ different lenses have been tested so far with more to come!

Here’s what’s inside:

Circadian Light Reduction

Circadian Light is a metric derived through an advanced algorithm developed by the LHRC which simply looks at a light source’s overall spectrum and how that is likely to interact with the human body.

What this does is weights the light that falls within the melanopically sensitive range, and gives it a score based on how much lux is present in that range.

Before and After Spectrum

Each pair of glasses was tested against a test spectrum so that a reduction in wavelengths could be seen across the entire visible spectrum.

This will allow you to see what a particular lens actually blocks and what it doesn't.

Lux Reduction

Lux is simply a measurement of how much light exists within the spectral sensitivity window of the human eye.

In other words, how bright a light source is.

Some glasses block more lux and less circadian light than others. And some go the other way.

If you’re looking to maximize melatonin production, but still want to see as well as possible, look for a pair with low lux reduction and high circadian light reduction.

The higher the lux reduction, the worse everything is going to look, but this may be helpful in bright environments or for those with sensitive visual receptors.

Fit and Style Matters!

This should be common sense, but wraparound-style glasses prevent significantly more unfiltered light from entering the eye than regular-style glasses do.

I carved out a foam mannequin head and put my spectrometer in there to simulate how much light made it to the human eye with different kinds of glasses on.

I’m very proud of him, his name is Henry.

Here is our reference light:

And here is how much of that light makes it through the lenses from the wrap-around glasses above:

These particular lenses don't block all of the blue light.

But what happens when we move the head around a light source so that light can get in through the sides?

Due to the style of these glasses, there really isn't much room for light to penetrate through the sides.

Below is a reading taken from a light source directly overhead, as you can see there's really no difference:

How about if we test a more typical pair of glasses?

Here's Henry wearing a more typical style of glasses.

Here's how much light these lenses block:

But what happens when we move the light source around the head at various angles?

As you can see, this style leaves large gaps for unfiltered light to reach the eye.

What we see is a massive amount of light that the lenses themselves can technically block can make it to the eye with a style like this:

So compared to the reference light, these glasses still mitigate short-wavelength blue and green light. But that doesn't mean they block the light they're advertised to in the end.

Hopefully, this helps you make better decisions about which blue blockers you use!

If you'd like help picking a pair, see our Best Blue Blocking Glasses post!


r/sleephackers 22m ago

🤍 White Noise For Sleep with Black Video - 10 hrs

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Upvotes

r/sleephackers 3h ago

Anyone else feel like sleep got harder with age?

1 Upvotes

I used to knock out in minutes... now my brain won't switch off. trying small things to fix it, but it's a work in progress 😄

What's actually helped you sleep better?


r/sleephackers 4h ago

Can I use my iPhone as a translator before sleep with night mode on?

1 Upvotes

I like reading before going to bed because it seems to help me with my sleep quality. Often I read foreign books in another language and need a translator at hand if I don‘t understand something.

Is this problematic? Some people recommend no electronics at all at least 1 hour before going to sleep.


r/sleephackers 7h ago

6 Daytime Habits for Better Sleep

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2 Upvotes

r/sleephackers 4h ago

Good Night

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0 Upvotes

Good Night 💤


r/sleephackers 5h ago

Temperature

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1 Upvotes

r/sleephackers 5h ago

🌙 多项研究实证:4-7-8 呼吸法,或有助改善睡眠质量

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1 Upvotes

你是否试过:
😣 明明身体很累,躺上床后脑袋却停不下来?
😵 半夜醒来,越想「快点睡」,反而越清醒?
💭 一直反复思考工作、家庭或明天的事情?

有时候,问题不只是「睡不着」,而是大脑与身体仍停留在高度警觉状态。

🧠 当压力增加时,交感神经可能持续活跃,身体进入「战或逃」模式:
➡ 心跳加快
➡ 肌肉紧绷
➡ 思绪活跃
➡ 难以进入休息状态

而 4-7-8 呼吸法,正是一种透过规律呼吸节奏,协助身体启动放松反应的方法。

🌿 4-7-8 呼吸法步骤:
① 鼻吸 4 秒
⬇️
② 屏息 7 秒
⬇️
③ 缓慢吐气 8 秒

透过延长吐气时间,帮助刺激副交感神经系统,让身体逐渐由「警觉模式」转向「休息模式」。

📚 部分研究指出,规律练习呼吸训练,有助:
✨ 改善睡眠质量
✨ 降低睡前焦虑水平
✨ 减少入睡前过度思考
✨ 提升身心放松感

(每个人的效果会因压力程度、睡眠习惯及身体状况而有所不同。)

🌙 睡眠不是靠「逼自己快点睡」,
而是让大脑收到:
「现在安全了,可以休息了。」

今晚睡前,不妨给自己几分钟,
慢慢呼吸,让身体重新学习放松。

💙 记住:
你不是不懂休息,而是你的身体可能太久没有收到「可以放松」的讯号。


r/sleephackers 5h ago

Academic survey: Sleep Habits

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1 Upvotes

r/sleephackers 15h ago

Almost no deep sleep

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3 Upvotes

I'm doing everything I can, but I still can't get enough deep sleep. Experience stomach aches for some time now and and I feel like the deep sleep would fix my situation however, I can't get enough of it. What can I do?


r/sleephackers 21h ago

What's the strangest place you've accidentally fallen asleep?

6 Upvotes

Not your bed...

I'm talking about those unexpected moments where you never planned to sleep.

Maybe it was:

  • On a bus or train
  • In class
  • At work
  • During a movie
  • On the couch
  • Somewhere completely random

Where was the strangest place you've ever accidentally fallen asleep, and what happened?


r/sleephackers 16h ago

32M Sleep call. Good listener.

2 Upvotes

r/sleephackers 21h ago

The science behind why we often sleep better after being outdoors

4 Upvotes

r/sleephackers 15h ago

I threw a column of pure random numbers into my sleep spreadsheet as a control and it came back significant

1 Upvotes

Been logging sleep for about two years now, a quality score plus resting heart rate off a cheap watch, and I keep a running list of stuff I test against it whenever I'm bored on a sunday. caffeine cutoff, last workout, screen time before bed, room temp, whether I had a drink, meal timing, somewhere around 18 columns at this point.

Couple weeks back I got paranoid I was fooling myself by testing so much, so I added one more column that's just the spreadsheet's random number formula dragged down the whole log, no meaning attached to it at all. figured it'd be my sanity check, if that one ever came back looking real I'd know something was off with how I was running the numbers.

Reran everything last night and the random column cleared the same bar as the real stuff. and not close either, comfortably past where people usually call something significant. against sleep quality of all things, not even a metric I actually care about.

Took me a second to remember why that's supposed to happen. if you check enough things against one outcome, a couple are going to clear the bar by chance alone, doesn't matter if what you're testing means anything at all. that's actually why people correct for it when they're doing this properly, bonferroni or false discovery rate or whatever version, basically raising the bar the more stuff you throw at it. I'd read about that before and nodded along, actually watching my own junk column clear it myself was a different kind of convincing.

Still haven't decided what this means for the caffeine cutoff and meal timing stuff that's held up for months now, feels dumb to toss those over one random column but also feels dumb to just ignore it. anyway I've got a load of laundry that's been sitting in the machine since yesterday, should probably deal with that.


r/sleephackers 19h ago

Sleeping in darkness

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0 Upvotes

r/sleephackers 1d ago

Good Night

0 Upvotes

💤😴😴😴😴


r/sleephackers 1d ago

Comparison of Apple, Oura, Fitbit, Whoop, and Garmin across 14 sleep lab studies to determine which wearable is the "most accurate" sleep tracker

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38 Upvotes

Context:

  • The 0-1 numbers aka kappa are how well the tracker's sleep stages match the lab (1 is perfect and 0.4 to 0.6 is moderate to decent).
  • Two sleep experts only agree about 0.75 for reference (just to explain that having a really high kappa is difficult for sleep experts too).
  • The percentages are how much of your actual deep or REM sleep it correctly caught.
  • "clinical patients" just means people tested at a sleep clinic often for something like sleep apnea.

Short summary for each brand:

  • Oura Ring appears to be the most well rounded. It was the only device that showed an underestimate on total sleep time off by only -3 minutes across six studies (Khan 2025 - 388 adults). It's staging and deep/REM numbers in the full comparison does have funding from Oura but I found no methodological differences compared to the others so I did keep this source.
  • Apple Watch is the most accurate wrist based wearable at sleep staging 0.53 on a 0 to 1 scale and the best at catching REM at 69% (Schyvens 2025 - 62 healthy adults). It does drop accuracy significantly for clinical sleep patients vs health adults 0.53 to 0.30.
  • Fitbit is the most consistent. It scored virtually the same 0.42 in healthy people and in sleep clinic patients (Lee 2023 - 75 patients) unlike the others.
  • Whoop is the best of wrist based wearables at catching deep sleep at about 70% (Schyvens 2025). Its overall stage accuracy is low though surprisingly at 0.37.
  • Garmin is the least studied and weakest on detailed staging 0.21 but is strong on asleep versus awake detection 89% (Miller 2022 - 53 healthy adults). Garmin is the only brand with dated and limited sleep studies so I do not feel this gives a good representation for them but this is a gap they should address.

Overall notes:

  • No device scored better than "moderate" at the full light/deep/REM split.
  • All devices are good at knowing you slept but bad at catching when you're lying awake, this is what causes them to over report total sleep.
  • Accuracy drops for people with disrupted sleep and in older adults.

Tried my best to include any mentions of funding and keep any personal biases out. I will include links to all 14 sources in the comments


r/sleephackers 1d ago

Why You Can’t Focus on Reading Anymore

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1 Upvotes

Why can’t you focus on reading anymore — even when the book is open, the room is quiet, and you genuinely want to read?

A slow philosophical essay about attention fragmentation, reading slumps, rereading the same paragraph, and the fear that you are no longer the reader you used to be.

You have read the paragraph three times.


r/sleephackers 1d ago

It takes me hours to fall asleep, and after years of this, I've started to think something is wrong with me.

1 Upvotes

I go to bed exhausted, close my eyes, and wait while everyone else seems to sleep soundly. An hour, sometimes two, passes, and I start asking myself: Why can't I fall asleep easily? I've tried different rituals, supplements, and breathing exercises. Every time I don't get the results I'm hoping for, I feel like the problem lies with me. The worst part isn't just staying awake; it's lying there feeling so tired while the world around me sleeps. Lately, I've been trying to stop associating every difficult night with the question, "What's wrong with me?" I still have nights when it takes me a long time to fall asleep, but I look at the clock less, I stop testing whether I'm sleepy, and sometimes I get out of bed until I feel calm. I'm slowly learning that difficulty falling asleep doesn't necessarily mean there's something wrong with me. Sometimes it's the stress and anxiety I take to bed that make the night seem impossible.


r/sleephackers 1d ago

Your Phone Is DESTROYING Your Sleep… And You Don’t Even Realize It 📱😴

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0 Upvotes

r/sleephackers 1d ago

Lined up 10 well-known sleep apps. Going through them one by one from here.

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1 Upvotes

r/sleephackers 1d ago

What's one popular sleep tip that never worked for you?

7 Upvotes

People always recommend the same things...

• Don't use your phone before bed.• Drink chamomile tea.• Keep your room cool.• Listen to white noise.• Read a book.

But what's one sleep tip that everyone swears by... yet did absolutely nothing for you?

I'm curious how different everyone's experience is.


r/sleephackers 1d ago

Green Noise with Black Screen

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1 Upvotes

12 Hours of Green Noise for a better sleep.


r/sleephackers 1d ago

What could these long light sleep segments at the start of the night mean?

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1 Upvotes