Amount of Sleep
Sleep time is the time between falling asleep and waking up. For example, you might go to bed at 9:51 p.m. and fall asleep at 10 p.m. If you wake up at 6 a.m., your sleep time will be 8 hours.
However, a longer sleep time doesn’t automatically mean better sleep quality. That’s why it’s useful to track the time you’re actually sleeping (sleep time minus interruptions).
If your sleep time was 8 hours (the time between falling asleep and waking up), but you tossed and turned for 59 minutes during the night, your actual sleep time was 7 hours and 1 minute.
However, interruptions as such aren’t a sign that you slept poorly because most of us experience several short and long interruptions during a normal night’s sleep.
Quality of Sleep
Sleep continuity is a metric that reflects the quality of your sleep. If you get a decent amount of uninterrupted sleep, you will likely feel more rested the next day than after a night with fragmented sleep.
There are no absolute numbers as to what constitutes an objectively good sleep continuity metric. Rather than comparing your sleep to anyone else’s, it’s best to track your sleep for a few weeks and find out what your baseline is – then compare your highest and lowest values to what is normal for you.
You can also track the sleep cycles (light, deep and REM sleep) your body goes through when you sleep and see how long you spent in each sleep stage.