If you're looking to improve the quality of your sleep, a sleep tracking app can be a useful tool to help you monitor and understand your sleep patterns. Two of the most popular sleep tracking apps for the iPhone are Sleepiest and Sleep Cycle, but which one is the best choice for you? In this article, we'll compare the features and effectiveness of these two apps to help you decide.

The Offerings of Sleepiest vs Sleep Cycle

Sleepiest and Sleep Cycle both offer sleep tracking functionality, however they each adopt very different approaches to tracking your sleep.

Passive sleep tracking is the sleep tracking method we use here at Sleepiest. Passive sleep tracking, (once enabled by you) allows us to track your sleep automatically. No need to open the app every day or press a "I'm going to sleep" button!

Instead it works quietly in the background and uses historical movement data of your device (provided by Apple or Google), passes it through our fancy sleep tracking algorithm and shows you how you slept (including in the week before even installing Sleepiest), as well as how your sleep improves after using Sleepiest.

This ability to view your sleep stats using both data from before you started using us, as well as while using Sleepiest we feel provides the transparency to you that Sleepiest is actually helping to improve your sleep... In fact we know from the passive sleep data of our current customers that on average you'll likely get 29 minutes extra sleep each night after starting to use Sleepiest.

Sleep Cycle on the other hand uses active sleep tracking. This form of sleep tracking uses the real-time motion data of your device and recordings from your microphone to try and determine if you are asleep or not. This is more intrusive given it needs listen to you all night using the microphone (if you choose to use the microphone rather than accelerometer). It's also far more taxing on your phones battery.

Active sleep tracking can however provide a few potential benefits - the fact it's collecting more data on a second-to-second basis means it can try and evaluate things like your depth of sleep / if you're in a "light" or "deep" sleep state. Because it has access to the microphone it can also potentially spot things like if you were kept awake due to noise outside.

One benefit active tracking offers with Sleep Cycles implementation is their offering of a "Smart Alarm", this is an alarm that will try wake up up when you're in "light sleep", with the aim of trying to wake you up when most comfortable. This is a feature Sleepiest doesn't offer as it isn't possible using passive sleep tracking.

This active tracking approach can lead to inaccuracy - noises from outside, or movements of your partner in bed can easily make the tracker think you're awake when you're not.

Scientists from the Mayo Clinic go as far as to explicitly warn against relying on sleep depth data from sleep tracking apps stating "Consumer sleep trackers are pretty accurate at tracking total sleep time" but stating "the only way to accurately identify what stage of sleep you are in is to measure brain activity during a clinical sleep study. None of the consumer devices on the market capture this kind of data".

Here at Sleepiest, this is why we chose to adopt the passive sleep tracking approach. If we don't have the data required to show you your sleep stages with any reasonable accuracy, we won't make it up and say that we do, and we won't try wake you up based on data that we know not to be accurate.

In reality no apps have the required data to show you accurate sleep stages without a peripheral capable of measuring your brain activity.

What we we do have (once authorized) is the movement data of your phone which we can use to accurately identify when you went to bed, and when you woke up, and we can display it to you in a nice way - so that's what we do.

If you're really looking to track the stages of your sleep in a very in-depth way / with a high degree of accuracy; the best option is likely from our friends over at dreem who offer a consumer headset and app capable of doing polysomnography.

Alternatively, Apple recently added support for tracking sleep states to their latest Apple Watch lineup. This doesn't measure brain activity and therefore won't be 100% accurate, but likely will be more accurate than apps using motion or microphone data given the access to heart rate and ecg data (and it's also likely more comfortable than wearing the EEG headset from dreem every time you go to bed 😅).

In terms of content - both Sleepiest and Sleep Cycle also offer sleep sounds, stories and meditations to help you sleep. Most of Sleep Cycle's content is locked behind a paywall, with only 2-3 bits of content available without subscribing. Comparatively Sleepiest has 100's of bits of content available for free without needing to commit to a free trial.

In terms of content offering; Sleepiest has over 500 original bits of content designed to help you get to sleep quicker, with 10 new bits of content every single week, many of which are also entirely free. Comparatively Sleep Cycle offers a far smaller selection of content, with much less frequent releases.

Sleepiest and Sleep Cycle both allow basic sleep tracking for free, with access to historical / long term data requiring a free trial or a subscription. Both Sleepiest and Sleep Cycle offer a 7 day free trial to explore the premium aspects of their services.

The price

Sleep Cycle costs $39.99/yr and offers no monthly subscription options. Sleepiest costs $49.99/yr or $9.99/mo. So Sleepiest is a little more expensive on a yearly basis, but offers a more affordable monthly option.

Ratings

Sleepiest and Sleep Cycle both have millions of downloads. Both have high ratings with the vast majority of ratings 5*. Both also have great user interfaces which are easy to navigate.

Detailed comparison

Conclusion

In terms of audio content to help you sleep; Sleepiest has a vastly larger library of content, and is putting out content on a much quicker basis than Sleep Cycle.

In terms of sleep tracking; Sleep Cycle uses active tracking to try detect the depth of your sleep. This requires you to press a button when you go to sleep each night, and when you wake up in the morning which can be frustrating. It also requires real-time access to your microphone and accelerometer which is rather more invasive. Worst of all however is that apps trying to measure sleep depth have been broadly criticized by sleep scientists as not being accurate and not something that's possible to do without capturing brain activity data; which would require peripheral such as a EEG headset.

Comparatively Sleepiest uses passive sleep tracking to estimate when you went to bed and woken up, something sleep scientists broadly agree consumer tracking apps are much more accurate at detecting.

Overall; if accurate tracking of sleep state / depth data is your aim; neither Sleepiest or Sleep Cycle are good fits and you should likely explore the options of getting a consumer eeg headset from dreem or grab yourself one of the newer Apple watch's.

If you're after an app to more broadly track when you went to sleep, wake up, and to help you get to sleep, then Sleepiest's passive sleep tracking makes collecting your sleep data trivial compared to Sleep Cycle and Sleepiest's vastly larger content library makes it the obvious choice.

Download the Sleepiest app here, and try our our passive sleep tracking tonight!