Understand Everything That Makes a Great Night's Sleep With New Sleep Metrics

Getting good sleep can help us live longer and healthier lives, with benefits like boosted immunity, lower risk of disease, better hormone regulation, improved nervous system management, and brain function. So what does good sleep look like? The answer might surprise you.

Understanding Sleep Consistency

Most people think getting good sleep is about securing eight hours of sleep each night. But many don’t know that the missing piece is consistency.  Sleep consistency refers to the practice of maintaining a regular sleep schedule and routine, including going to bed and waking up at the same time each day. A 2017 Harvard study discovered that students with consistent sleep and wake times had higher GPA’s than others, despite not actually getting more sleep. 

According to sleep expert Dr. Allison Brager, maintaining a solid schedule and sleep consistency is “the only true way to optimize the release of melatonin,” which is the hormone our brains produce before bed and in response to darkness. 

Our data shows that better sleep consistency contributes to:

• More REM sleep, the mentally restorative stage of sleep
• Increased slow wave (deep) sleep, the physically restorative stage
• Lower resting heart rate
• Higher heart rate variability (HRV)
• Improved mental health

WHOOP quantifies how similar your sleep and wake times are over a 4-day period and provides a score on a 0-100% scale. Higher Sleep Consistency indicates more similar bed and wake times, while lower Sleep Consistency indicates greater variability in night-to-night sleep timing. So even if you get 100% of the sleep WHOOP recommends, you could still be missing out on potential sleep-related benefits if you are getting this sleep at inconsistent times. 

What is Sleep Efficiency?

Sleep Efficiency is a simple but powerful metric, and is the percentage of the time you spend in bed that you are actually asleep. Sleep Efficiency is considered a measure of sleep quality, and looking at it alongside your other sleep metrics can help you understand where you can start to improve your sleep. For example, if you spend 8 hours in bed, but only sleep for 5, your sleep efficiency is going to be lower than if you spent 8 hours in bed and 7 hours asleep. 

WHOOP tracks your Sleep Efficiency helping you understand how much of your time in bed is spent awake and make changes in your bedtime habits if you’re not getting enough sleep. Health can have a major effect on this if you’re experiencing illness, chronic pain, and injuries it may hinder your ability to get to sleep and sleep through the night. Sleep problems including sleep apnea, circadian rhythm disorders, and insomnia also affect how much sleep you’re getting. Additionally, pregnancy can impact a multitude of systems and functions, including your ability to fall and stay asleep. All of these are disruptions that often result in low sleep efficiency and a poor night’s sleep.  

Knowing Your Sleep Debt

Roughly 1 in 3 adults struggle with sleep debt on a regular basis, according to research from the CDC. When you don’t sleep as much as you need to, you start to accumulate sleep debt. Also known as a sleep deficit, sleep debt is the difference between the amount of sleep your body requires and the amount you actually get. Sleep debt builds up over time, so by sleeping less than usual for multiple nights in a row your sleep debt can progressively get worse and worse. WHOOP tracks your sleep debt and calculates how much sleep you need in order to catch up.

The Importance of Restorative Sleep 

Restorative sleep refers to how much time you spend in Deep (slow wave sleep) and REM (rapid eye movement) sleep each night. Deep sleep is known as the physically restorative stage of sleep, and is when many of the body's regenerative processes happen. REM sleep is known as the mentally restorative stage of sleep, where most of our dreams occur, and short-term memories are converted into long-term memories. Together, maximizing restorative sleep improves your recovery, your cognitive function and ability to focus during the day, as well as support vital body processes. 

The optimal amount of restorative sleep for most people is about 40-50% of the total time asleep in these restorative stages. If you want to get more restorative sleep try to:

• Spend more time in bed
• Establish a consistent sleep and wake time routine 
• Limit screen time right before bed

The sleep trends in your WHOOP app help you unpack your restorative sleep. You can also see your restorative sleep trends over time for a closer look at the total number of hours and ratio of restorative sleep. Understanding patterns like this can help you build routines that maximize your recovery and improve other metrics like your heart rate variability, one of the key metrics for determining your body’s readiness to perform each day.  

How to Access Your Sleep Trends

Getting good sleep consists of a combination of your Sleep Consistency, Restorative Sleep ratio, in addition to your Sleep Debt and Sleep Efficiency.  To view your Sleep Trends, you can go from the Home tab and scroll down to Key Statistics, or tap into Sleep and scroll down to view your Trends. 

Improving Your Sleep

If you’re not sure where to start with improving your sleep, prioritize your consistency over everything else. Improving one metric at a time with small changes can make a big difference. Sleep Planner will help you understand your ideal sleep and wake times, you can even set a haptic alarm to wake you up when you’ve hit your sleep goals. You can also ask WHOOP Coach questions about your sleep and Sleep Trends for personalized recommendations based on your unique data.