A molecule is the smallest particle in a chemical element or compound that has the chemical properties of that element or compound. Molecules are made up of atom s that are held together by chemical bonds.
Some studies have shown that your deep sleep should at least be 20% of your overall sleep. It means that since most adults need 8-9 hours of sleep, they will need about 1.6-1.8 hours of deep sleep to feel fully functional next day. However, the time of deep sleep is changed and that's mainly due to the change in the sleep need of different group of people. For instance: Age Group.
You need to sleep eight to 10 hours continuously to cycle through these stages three to four times. Every time you cycle the length of the REM sleep increases while the deep NREM decreases until you have a good 30 minutes in dream sleep without any deep sleep occurring, that is considered healthy sleep.