While sleeping, some people may leave the light on or dim it down, so that perhaps it is equal to a 35W or 20W regular light bulb. In this case, is it true that the pineal gland in our brain won't secrete melatonin during the sleep, and therefore have harmful effects to the human body?

What if we occasionally cover our body and even the head temporarily using the quilt during our sleep, so that there is close to no light that gets to our skin (as it is said that even light on the skin can affect the pineal gland to not secrete melatonin).

There are some variations to this, and I wonder if it is similar:

  1. If there is a street light or community light post outside of the window, so throughout the night there is as if a 10W or 20W light bulb inside the room.

  2. If the light in the room is turned off, but the hallway has a ceiling light and it is on, while the bedroom door is about 80% closed but some light in the hallway can come in.

  3. Some people may leave the TV on (and possibly turning the volume to quite low) while sleeping. It is said that blue light might have the biggest effect out of the light spectrum on our pineal gland to not secrete melatonin, as most electronic devices do, such as a smartphone screen or LCD/LED TV screen). So if we turn off the light but leave the TV on, then it might still be the same issue or even more so.

  • I like Bob's version of the question a bit better just because it's more specific about the effects. "Is it harmful" is really vague and not really the way scientific questions about health get asked. It's also not clear if your actual question is "is this harmful" or "is this harmful because of differences in melatonin production" – Bryan Krause Dec 7 '19 at 0:07
  • that question is about "sleep quality". This question is about "possible harmful effect to human body". They are different – nonopolarity Dec 7 '19 at 5:42
  • After re-reading both questions multiple times, I agree I acted in haste and they're not exact duplicates, but your question lacks prior research while the other one doesn't. Who says the pineal gland won't secrete melatonin during sleep under low-light conditions? If you're going to ask us to address claims, you need to show us the claims. – Carey Gregory Dec 7 '19 at 6:07
  • Comments are not for extended discussion; this conversation has been moved to chat. – Carey Gregory Dec 7 '19 at 16:25

Browse other questions tagged or ask your own question.