I take a nap almost every day, sometimes I wake up really refreshed and ready to go to my class, but other times I wake up feeling more tired than when I went to sleep. This got me wondering about if it was the amount of time I was asleep, or if my drowsiness after a nap was more because of how deeply I was sleeping.

The American Heart Association  describes how our brains are very active during sleep. Normally one would think that this would be a time for our brains to relax and chill, but actually chemicals in our brains determine how well of a nap or good night sleep we will get. This will in turn help determine how awake we will feel after waking up. These chemicals are called neurotransmitters and act on different neurons in the brain to determine what stage of sleep we will be in. Different foods and medicines ingested before sleep can influence these neurotransmitters and change the balance of these signals. For example, caffeine can stimulate some parts of the brain which can create insomnia, antidepressants can hinder the REM cycle of sleep, and alcohol which is used to help people fall asleep keeps that person in a light sleep and can awakened easier rather than if they were in a deeper sleep.

There are five stages of sleep: stages 1, 2, 3, 4, and REM (rapid eye movement) sleep. When this cycle is over (when REM is completed) the cycle continues back to stage 1 and starts over. On average, one complete sleep cycle (from stage 1 to REM) lasts about 90-110 minutes. As the night progresses and a person is asleep for longer, the REM cycle lengthens in time, and the amount of time spent in deep sleep decreases. On average, people spend the majority of their sleep in stages 1, 2, and REM.

Obviously sleep is important to people just for their own sanity, but sleep is also necessary for health and survival. In a study done in rats, who generally live about 2 to 3 years, rats who were sleep-deprived only lived for about 3 weeks. Additionally, the rats who were sleep-deprived showed evidence of a weaker immune system. Without sleep, we are cranky, may not be able to remember things, and cannot function properly. In another study done on rats, the neurons that are used during the day with stable emotions and social interactions are decreased during deep sleep. This shows how sleep helps regulate these hormones and can lead to optimal social interactions and emotional stability while awake.

While all this information I found helped me to understand why sleep is so important, I was still curious as to how sometimes I wake up more tired than when I go to bed. Normally, that happens when I sleep for a really long time, like when I wake up at 12 or 1 in the afternoon. During naps, however, I haven’t been able to figure out what is the optimal amount of sleep in order to wake up feeling refreshed. Throughout my research, I have come to the conclusion that it is not necessarily the amount of sleep a person gets (of course that is important too) but it is the quality of sleep. The best sleep is one the completes an entire sleep cycle. If a person wakes up mid-cycle, they are more likely to feel fatigued and drowsy when they wake up. Completing a sleep-cycle is the optimal amount of sleep of a nap. You can complete as many cycles as you have time for in a nap, but the most important part is waking up at the end of REM rather than in the middle of a cycle. There is no real way to control this, because we cannot really control when we wake up.

What is Sleep?

http://www.helpguide.org/articles/sleep/how-much-sleep-do-you-need.htm