Lights and Depression… and a lot more!!

In class on Thursday, we read an article for our pop quiz on the effects of exposure to dim lights at night on depression, and instantly this caught my eye.  I have always been the kind of person to sleep with a dim light on in the room.  Whether it be a lamp that I left on or the television, very rarely do I sleep in a completely pitch black room.  My favorite time of the year is when my mom puts the window candles in so I can fall asleep with the light of the candle glowing into my room.  Naturally, I never saw this as a possible cause of depression, but since reading that it might be, I am starting to second guess my habit of sleeping with a dim light on.  When we read this article in class, I was very surprised in the findings that showed alterations in the hippocampus of hamsters after being exposed to dim light at night, and I was not too sure how accurate this one study on hamsters could be, so I decided to do a little bit more research on my own.


During my research, I found another experiment done on hamsters at the Ohio State University Medical Center, and in their research, it showed that signs of depression were observed after hamsters slept with a light on at night in a very short amount of time, one or two weeks to be exact.  To me, this seemed crazy, but with scientific evidence to prove it, it also seems to be very reliable data.  Another reason why to see this data as reliable is the experiment’s ability to be replicated.  In science, it is very important that the results can be found again to prove that it all did not simply happen by random chance.  In this experiment, the researchers also discovered differences between the hippocampus in the hamster’s that slept with a dim light on and a normal, healthy hamster that did not sleep with a dim light on.  In the hippocampus of a person with depression, similar alterations in the hippocampus to the ones in the hamster would be seen, signaling that there might be a connection between sleeping with a dim light on and depression.  The researchers hypothesized that this change could come from the lack of melatonin, since the production of this hormone is being stopped or slowed down by the light at night.  This is exactly like the article that we read in class, showing that this is a commonly accepted theory.

Now, I know most of you are reading this and doubting that a little dim light while you’re sleeping could really cause all of this, because that is how I felt after class on Thursday, but it seems that this data has some truth behind it.  According to the article that I previously referred to, anything that affects your production of melatonin will affect your mood.  While coming across this information on the effects of light at night on depression, I also ran into a few other reasons why not to sleep with a source of dim light on.  By interrupting the production of melatonin, there are also many other risks involved that I was never aware of before doing this research. Along with depression, a lack of melatonin can also lead to multiple other mood disorders.  On top of that, a lack of melatonin can also lead to obesity, which goes hand in hand with diabetes.  But the one that concerned me the most and got my attention was the correlation between too much light at night, or not enough melatonin, and cancer.

Melatonin is a very essential hormone when it comes to being healthy.  The brain usually starts to naturally make or produce melatonin right around the time that you should be going to sleep, between the hours of nine and ten at night, but any sort of light source will send messages to your brain to be alert and not go to sleep, causing the secretion of melatonin to be stopped.  Not only is sleeping with a light on bad for your health, but really any source of bright light after ten could be putting you at risk for major health problems.  This lack of melatonin can cause all of the problems stated above.


As I recently found out, melatonin is actually very important while to fight an deteriorate cancer cells, but not having enough melatonin could lead to a higher risk of developing cancer.  Melatonin also regulates your circadian rhythm, which is your body’s natural clock that keeps you on a normal schedule.  By upsetting your circadian rhythm with a lack of melatonin, it can increase your appetite and increase your weight.  In an experiment done with mice here, if a light was left on for the mice at night,  they would eat more of their food because they were awake longer even though they were given the same amount of food that they would get on a normal day, and from this, they gained a noticeable amount of weight, showing a strong correlation between light at night and weight gain.  However, a second experiment was then done where the mice’s food was limited to only the certain times a day that a mouse would usually eat, and then there was no weight gain.  This shows that the mice probably only gained weight because they felt the need to eat later at night since they were still up.  In my opinion, this is a real problem among people, because I know, at least personally, that when I’m up late studying for an exam, I always eat a midnight snack.

Luckily for us, most of this can be reversed!! In the same experiment done with the hamsters above, their symptoms of depression went away when they were given a normal night’s sleep without any dim light interrupting them.  I know that sometimes eight hours is a lot to ask for in all of our hectic schedules, so if eight hours is impossible, at least try to sleep in complete darkness when you do have the time to sleep.  Personally, my opinion on this whole subject has completely changed now that I am more informed.  I walked out of class on Thursday thinking it was crazy to change our sleeping habits after one experiment with hamsters, but now I think the best thing to do is to turn off all sources of light while sleeping. Like Andrew said at the end of class while discussing the last question of the pop quiz, you might as well turn off all the lights as a precaution because that sounds a whole lot better than being depressed! Better safe than sorry!


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3 thoughts on “Lights and Depression… and a lot more!!

  1. Taylor Lexi Weinstein

    Hello Jessica
    While reading this article and learning about dim light in class, I was also surprised by the facts and how dim light could affect a person so much. For me personally at night I need to sleep with pitch black lighting. However, sometimes i do tend to fall asleep and have the TV still on. After reading about how it could cause cancer and obesity I am going to start to really take percussion and make sure I turn the light completely off. While I was researching I was looking up informtaion about why people should never sleep with TV or Dim Light. My findings are astonishing. In an article I found it talked about how hamsters were effected and they got depression and In the article according to live science it stated, “The hamsters exposed to light at night showed behaviors indicative of anhedonia (depression-like response in which one does not find pleasure in favorite activities), and changes in the hippocampus of the brain. ” Which was what we talked about in class. Who new that something we all thought was innocent could affect our health in this dangerous of a way.
    Here is the article it further more talks about some information of why people should sleep in total darkness like I do:

  2. Brooke Barrett

    I find this so interesting! I have Christmas lights in my room and I always loved having the dim light to light up my room. After class on Thursday and reading your blog, I definitely turn them off earlier than I usually did. I also know a few people who take melatonin pills to help them sleep at night. I wonder if people would turn off the lights, TV, their phones, or anything that generates light, if they would not need to take the melatonin anymore.

  3. Asaad Saleh Salim Al Busaidi

    Hi Jessica
    First of all, I am not the type of a person who keeps light turn on at night for two reasons. One of them is that it would increase the electrcity bill if you pay by yourself. The other reason is that I used to sleep in a dark room when I was young. Secondly, it has surprised me that keeping one light in can cause obesity and of course depression. My roommate keeps his dim light on all the day and I will certainly let hin read your article. Thanks. Here is a link for another type of light that costs less, works better and can be altered.

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