How Many Hours Should You Sleep to Feel Refreshed?
Your sleep cycles are consisted of 90 minutes of orthodox sleep (the sleep without dreams) and 30 minutes of REM sleep (deep sleep). For this reason, it is best to wake up when a sleep cycle is over, which is 120 minutes, or 2 hours. So it is best to sleep an even number of hours to feel refreshed (For example, 4, 6, or 8 hours).
But of course, you should consider the quality of sleep, not just how long you sleep. And the best time for a quality sleep is between 2-4 am in the morning. It is because people tend to sleep better when their body temperature is low, and human body temperature reaches its highest around 2 pm, and its lowest between 2-4 am. Also, it is better to sleep when your pulse is low, but your pulse starts to increase around 5 am, so it is not ideal to start falling asleep during that time. Lastly, human brain functions the best during 6-8 in the morning. So if you are the type who sleep and wake up late, you might be missing out on the part of the day when you can work more efficiently.