The biological process characterized by reversible unconsciousness, unresponsiveness to external stimuli and motor passivity.
32
votes
3answers
749 views
Why did the process of sleep evolve in many animals? What is its evolutionary advantage?
The process of sleep seems to be very disadvantageous to an organism as it is extremely vulnerable to predation for several hours at a time. Why is sleep necessary in so many animals? What advantage ...
12
votes
1answer
618 views
What causes REM atonia to be lost in sleepwalking?
I understand that in normal REM sleep the voluntary muscles are in effect paralysed in order to prevent an individual acting out their dreams. This paper indicates that there are likley to be ...
10
votes
1answer
173 views
Why do we feel tired if we sleep excessively?
When we eat, finally we feel full. I know which mechanism causes the sensation of being full. But when we sleep excessively we often still want more sleep. Why does this happen? Is there a mechanism ...
9
votes
1answer
101 views
What light intensity starts melatonin release in humans?
I'm interested in whether any studies have determined the intensity of light at eye level that starts melatonin release in humans.
I know that:
melatonin release is suppressed by blue light with ...
9
votes
1answer
72 views
Does sleep in humans re-structure based on the expected sleep time?
I've read about anecdotal evidence that human brain has a fairly good internal clock that can be used to judge the amount of time that has passed. I'm wandering if there are any mechanisms in the ...
8
votes
2answers
266 views
Is it possible to live without health problems sleeping one day and not the other?
Basically, I want to know if it would be humanely possible to sleep one day, skip the next, sleep, skip, sleep, skip, etc, with a 8 hour sleep time.
If you need any extra information, let me know.
8
votes
1answer
942 views
Effects of Polyphasic vs Monophasic sleep in humans
Why do humans practice monophasic sleep cycles?
When altering one's circadian rhythm to a Polyphasic sleep schedule, how much would that affect development?
Is Monophasic sleep (once per day) ...
7
votes
1answer
275 views
Disadvantages of unihemispheric sleep
Is is well known fact that marine mammals and some birds can sleep with one brain hemisphere at a time, since it's essential for their survival.
However, at least in my opinion, such mechanism would ...
6
votes
1answer
35 views
Is there a normal human melatonin concentration to light level curve?
I'm looking for a graph or a curve that would show the typical concentration of melatonin in blood or saliva for humans over 24 hours. It would be good to know the photoperiod for the same human as ...
6
votes
1answer
71 views
How does one maintain balance sleepwalking?
Anectodal. Feel free to shoot it down.
Walking is an acquired skill; As far as I'm concerned exhaustion causes disorientation. Even after waking up it sometimes takes a second or so to get balanced.
...
4
votes
1answer
94 views
Can humans shorten their sleeping patterns?
Can sleeping patterns be trained, or are they genetic? I read that a human needs to sleep at least 4 hours. Can sleeping time be reduced without having a negative impact?
4
votes
1answer
68 views
What causes humans to be sleepy?
Is there a hormone or group of hormones that regulates when we feel sleepy late at night, or in the morning? Or is sleepiness caused by some other non-hormonal mechanism? (e.g. pure psychological, ...
4
votes
1answer
220 views
Why do people look different after a long sleep?
What happens during a long sleep that makes people look odd when they have just woken up? Why doesn't the same phenomenon occur in the case of a person who lies down for an extended period of time, ...
4
votes
0answers
21 views
How are our senses dimmed during sleep?
Our senses are not as sensitive during sleep compared to wake. There is an arousal threshold during sleep that only when it is overcome will it wake a person up. My question is how is this arousal ...
3
votes
1answer
69 views
How are melatonin levels measured in humans?
I'm wondering how it is possible to measure diurnal variations of melatonin levels in humans. I keep reading that there should be a large difference in amplitude between melatonin levels measured at ...
3
votes
2answers
53 views
Do dolphins really sleep?
I have always wondered, if dolphins sleep with one eye opened, do they really sleep at all?
According to this article dolphins indeed shut down their brains.
I already googled it. No help from ...
3
votes
1answer
164 views
Human sleep cycles and dream times, what influences the timing and intensity? Sleep history included
I'm doing sleep and dreams research and have developed an iPhone application to help me track my bedtime, rise time, sleep onset and also mark dreams. The app also monitors overall activity overnight ...
3
votes
0answers
37 views
What causes adenosine build up in the brain when awake?
Adenosine is an important hormone in sleep regulation. It is postulated that when a person is awake, there is a build up of adenosine in the brain, which inhibits the neurons in the brain, and ...
3
votes
0answers
49 views
What controls the feeling of discomfort/comfort before and after sleep?
I'm interested in which biological systems or hormones are involved in the following phenomenon:
Before sleep it may be difficult to find a comfortable position, and muscular aches and pains are more ...
3
votes
1answer
37 views
The fundamental importance of R.E.M. Sleep. (Rapid Eye Movement)
Question:
I know that experiments have been conducted to determine the importance of R.E.M. sleep in our sleep cycle. It is particularly important for learning, information synthesis, and recovery ...
2
votes
1answer
105 views
Are there any multi-cellular organisms out there that do not sleep?
Looking around I see animals - ants, bees, birds, lizards, roaches all the way up to humans appear during a part of the day and not other parts. I would guess there is a sleep/recovery cycle involved.
...
2
votes
2answers
45 views
What mechanism suppresses melatonin release in humans?
I'm looking at melanopsin, a photo pigment in the human eye. One of its actions is to trigger suprachiasmatic nuclei SCN to suppress melatonin release. I'm interested in learning what is the exact ...
2
votes
1answer
34 views
Are (baseline) high blood levels of melatonin associated with either circadian rhythm or mood disorders?
(Exogenous) melatonin is administered at night for treatment of circadian rhythm disorders, but melatonin taken during the day is linked with depression.
I would like to know if high blood levels of ...
2
votes
0answers
454 views
Do humans sneeze or cough in their sleep?
As far as I know, I've never seen anyone sneeze or cough while they're sleeping. Google wasn't very helpful either; a lot of contradicting claims.
So the questions remains: do humans sneeze or cough ...
2
votes
0answers
35 views
Physiological or molecular difference before and after sleep?
I know that the details of the process of sleep aren't entirely known, but have always wondered why I feel rested after sleep.
Biologically, what differences can be directly observed in the human ...
1
vote
1answer
94 views
Why does non-continuous sleep makes you feel tired?
Let's say, hypothetically, that you fell asleep at 10PM, and you were woken up by a noise at 1AM. If you went back to sleep immediately and woke up at 6AM, you will feel tired even though you had ...
1
vote
1answer
60 views
Serotonin - Does being aroused make you sleepy?
My Psychology text book says Serotonin causes "Sleep, arousal levels and emotion"
Does this really mean that when you are being aroused, Serotonin is released, which in turn makes you sleepy? If so, ...
1
vote
0answers
19 views
What is the mechanism by which Melatonin increases dream vividness and intensity in humans?
I'm looking at the wikipedia article on Melatonin and noticed that it mentions vivid dreaming caused by melatonin. I have the "Melatonin and the Biological clock" pamphlet referenced in the article, ...
1
vote
0answers
30 views
Does Dorsal Raphe Nuclei firing pattern change in response to voluntary breathing?
I'm reading this paper, which discusses how Serotonin may be involved in motor functions of mammals: 5-HT and motor control: a hypothesis .
The paper includes the following diagram of the Dorsal ...
1
vote
0answers
19 views
Can we make any judgements about sleep or readiness to sleep from a heart rate metric and/or pulse oxymetry?
I'm looking at inexpensive and un-intrusive ways to quantify the state of human body/mind . One of these is Actigraphy, which is a study of human motion over time. This can be done with an iPhone ...
1
vote
0answers
96 views
What is the timing of information assimilation within a human brain?
A little background: I'm an avid dreamer and have great dream recall, sometimes up to 5-7 per night.
In my experience, I can sometimes trace some elements of the dream to an event that occured ...
0
votes
0answers
25 views
Are there different metabolic pathways leading to “sleep”?
First of all, I apologize if this question does not belong on biology.stackexchange.
I've long been interested in sleep and recently postulated this question in light of reading about ...
0
votes
0answers
90 views
Can the sleep/wake cycle be influenced by non-visible spectrum electro-magnetic radiation?
I've been reading a few papers on Melanopsin and Suprachiasmatic Nucleus (SCN), and see that the sleep/wake transition is ...
