There’s different levels of sleep. Its not just how much sleep we’ve had in terms of hours.

There’s an interesting article over at Calm app’s website.

The article explains that deep sleep, also known as slow-wave sleep, is a crucial stage of the sleep cycle responsible for physical restoration, memory consolidation, immune function, and emotional well-being. Adults typically need 13–23% of their total sleep time in deep sleep, which translates to about 1 to 2 hours per night if sleeping 7–9 hours