Why we dream
What's going on inside our brains?
It's difficult to measure a dream, you can't taste it.
You can't see other people's dreams, and if you ask them to tell you what they dreamt,
the results are almost always unreliable.
In 1952, researchers at the University of Chicago found this.
It's a unique type of electrical activity that occurs during a certain stage of a person sleeping.
When researchers awoke people during this stage,
they almost always reported that they had been dreaming.
Also, at the same time, during this stage, people's eyeballs are going crazy,
rapidly darting all over the place underneath their eyelids.
This stage called Rapid Eye Movement, REM.
Review - About sleep - Host: Renee
(Briefing: sleep) (03) 11/10/2021
Host: Renee
(Briefing: sleep) (03) 11/10/2021 
Sleep cycles during one night
Sleep researchers have found that sleeping people undergo a fairly consistent pattern of sleep stages, each lasting about 90 minutes.
As you can see in Figure, “Stages of Sleep,” these stages are of two major types: rapid eye movement and non-rapid eye movement.
Most of the dreams occur in the REM stage. During REM stage our muscles shut down, and this is probably a good thing as it protects us from hurting ourselves or trying to act out the scenes that are playing in our dreams.
A few of the more prominent theories about why we dream
- We dream to fulfill our wishes. 我們為了滿足願望而做夢。
- We dream to remember. 我們為了記得而做夢。
- We dream to forget. 我們為了忘記而做夢。
- We dream to keep our brains working. 我們為了讓我們的大腦保持運作而做夢。
- We dream to rehearse. 我們為了演練而做夢。
- We dream to heal. 我們為了痊癒而做夢。
- We dream to solve problems. 我們為了解決問題而做夢。
Special dream type: Lucid dreaming
We can also be inside a dream and know that we're dreaming. This phenomenon is known as lucid dreaming.
It's particularly attractive, because while in a lucid dream, We can make conscious decisions about what we do.
We’re in control, but achieve a lucid dream is not an easy thing.
- The first strategy towards lucid dreaming is keeping a dream journal.
Keeping the journal improves your ability to recall dreams, and helps facilitate lucidity.
So every time you wake up, write down what you can remember, even if it's nothing, just to form the habit.
- The next step is performing reality checks.
In a dream, something as simple as reading a sentence, counting your fingers, or checking the time can often go astray.
The key is to do these reality checks often when you're awake.
This way they become second nature and when you're dreaming you're likely to perform the same test and realize that something's wrong.
- After this comes a technique known as Mnemonically Induced Lucid Dreams or MILD.
As you're falling asleep, begin to think of a recent dream, and imagine yourself becoming lucid.
The idea is to reinforce the intention to realize you're dreaming in your dream.
Keep repeating the phrase "I will have a lucid dream tonight."
The highest rates of success tend to come if you wake up in the middle of the night get up for 30 minutes, and then go back to sleep with these intentions in mind.
Dream & Sleep quality
夢境的記憶
（出處：睡覺做夢原因是？這種人容易記得夢境 - Hello 醫師 (helloyishi.com.tw)）
這篇文章說到，記不記得夢境與以下 4 種因素有關：
1. 性別：根據調查，女性比男性更容易記住自己做過的夢，但也比男性更容易做惡夢。
2. 年紀：成年期，也就是大約 20、21 歲開始，人類對夢境的記憶力就會開始衰退。
3. 人格特質：研究顯示，常常做白日夢、善於創意和思考、懂得正念冥想的人，更容易記得自己做夢的內容。比較實際、或只注重自己外在的人，則較容易忘記自己做過的夢。
4. 睡眠障礙：失眠的人會比一般人更記得自己的夢，嗜睡症患者的夢境，則會偏向負面。不過如果睡覺的時間不夠長，經歷的 REM（快速動眼） 時期就會減少，那就很難記住自己的夢。
〔關於作夢與睡得好不好，這篇文章認為〕：
做夢這件事並不會影響睡眠，記得自己做過的夢也很正常，不代表睡眠品質不佳。但如果「做夢」讓我們感到精疲力盡、壓力大，甚至是情緒低落，那就是警訊了，當長期在這種狀態下，可能要考慮諮詢醫師。
夢與潛意識
（出處：夢境是記憶儲藏室，3種「預知夢」是存在的！夢境諮詢師領進夢中，看清自己真面目 - 幸福熟齡 (businesstoday.com.tw)）
此文作者 心理諮商師 李香盈有記錄夢境的習慣，因為許多夢境都是潛意識的作用，透過記錄 & 解析夢境也是與自己進行深度對談的一種方式。
值得注意的是，作者說：每個夢都非常『個人化』的。
「即使人類的心理歷程可能有相同的感受、共同的聯想，但同樣一個夢境，例如『逃亡』，別人的潛意識訊息，不代表是你的；所以許多民俗解夢、心理測驗，都只能做參考，你還是要探索內在，找到解答。」
〔關於作夢與睡得好不好，這篇文章認為〕：
作者以自己的經驗分享，她每天都做好幾個清晰的夢，可是卻不覺得累；因為真正會讓我們感到疲累的，是心裡深處的壓力與情緒。
綜上，兩位醫師及心理師一致認為，造成醒來覺得疲累的原因在於內在的壓力與情緒。這些壓力與情緒也容易讓人作惡夢，間接導致夢中驚醒而影響睡眠。
【為什麼要睡覺】一書提到，關於日有所思夜有所夢這件事，哈佛大學做過一項研究，證實夢境中僅有 1%~2% 的內容與白天清醒時的生活事件有明確的重播現象；然而白天清醒時的情緒主題和關注點，則有 35%~55% 會出現在夢境中，強烈而清晰。
【為什麼要睡覺—Matthew Walker】一書，有更多關於睡眠與作夢的研究，Hyread 上也有電子書可以借閱，一起推薦給大家。
書中有趣的小知識—『科學捕夢網』：2013 年日本的一個研究團隊利用磁振造影對參與者睡覺與清醒時的腦部活動與夢境進行詳細的紀錄、分析與精煉，得到一個腦部活動對應夢境元素的資料庫。最終，得以僅透過磁振造影的掃描結果，準確判定參與者夢到的內容，正確率相當顯著！