It doesn't matter as long as you get enough sleep. People will tell you otherwise because people typically don't do 1am to 10am.... they do 1am to 7am. To do that they use alarm clocks and coffee. In the long run, it will catch up to you.

It really depends on the individual. I don't know if there is any research showing that people who sleep at certain hours of the night are healthier than others. Even the amount of sleep for optimum health is highly subjective because everyone needs a different amount. Some people live well with 5 or 6 and others need more like 10. Some studies have shown that people who sleep less than 8 hours a night (but more than 4 I think) live longer than people who sleep more. But from what I understand there's nothing to suggest why that is, so it might be circumstantial.

On a general level people's sleep habits are dictated by the circadian rhythm where our bodies have a built in sense for sleep and being awake, and those cues are darkness and daylight. The rhythm is definitely affected by environmental factors, like the change in sunset/sunrise times at different seasons. Same with traveling to a different time zone - our bodies adjust to the difference and we learn to sleep and wake with the sunset and sunrise in the new location.

In industrial societies where we aren't getting up with the dawn and going to bed at dusk for agriculture lifestyles, sleep is dictated by other schedules, like school and work. We have to adjust, those are the circumstances of our culture.

In terms of your health, it's probably best to see how your sleep schedule affects your life and everyday functioning. Is it a schedule that works for you? Are you noticing side effects when you're awake? Are you exhausted all the time, or do you have trouble not falling asleep while working/reading/driving/sitting etc? Do you have problems being able to keep appointments or meetings or hanging out because your sleep cycle is so different from everyone else's?

If you're noticing that kind of thing, see a doctor.

Good description of circadian rhythm posted by McSkitters.

It's true that your natural sleep system is geared to sleeping at night and being active during daylight.

Your sleep system is largely regulated by light. Light is the environmental cue that your biological clock uses to synchronize with your natural circadian rhythm. And circadian rhythm, along with sleep drive (a separate neurologic process) largely controls sleep.

There are a number of neurologic systems at play with sleep, and a number of neurotransmitters involved, not the least of which is melatonin.

Melatonin is secreted by your pineal gland, which is stimulated by light. Simply put, the onset of darkness at night tells the pineal to turn on melatonin, light in the morning tells it to shut down. That's oversimplified, but the basic idea.

The fact that we can control artificial lighting to such a large extent today makes it possible to adjust to schedules that are less dependent on natural sunlight.

So yes you can sleep during the day and be active at night, but it takes more work and discipline. Especially important is blocking out noise and light during the day while you sleep.

What I suspect may be happening with you at age 19 is you may be experiencing a bit longer circadian rhythm than the normal 24 hours. Some people your age experience more of a 26 to 30 hour day. That's common from about age 14 through 30. The effect is to gradually lead one toward feeling drowsy progressively later and also to get up later.

You can effectively counter this by just setting and keeping a consistent wake up time every day.

I've been doing quite a bit better lately. I found out that it appears I only need around 7 to 8 hours of sleep. It's very strange but if I get uninterupted(not waking up momentarily even) then I feel perfect and usually wake up after about 7 to 8 hours of sleep. Even though it shouldn't, if seems like if I get woken up by a noise even momentarily, I need that 9 to 10 hours of sleep instead.

Although I've always been a somewhat insomniac, when I sleep, I rarely if ever experience the frequent waking up symptom. My two main problems are typically waking up earlier than I want and feeling tired but not being able to go back to sleep, or not being able to fall asleep period.

Like I said, I think me sleeping less is going to decrease the wake ups really early. Last night I broke my schedule though because of a family party and went to bed at 3:30 A.M. and woke up at 12:20 P.m. Before I was going to bed around 2 P.M and waking up around 10. That's my only complaint lately. I want to cut down my bed time to around midnight instead of 2. Not sure how to do so however. I fear if I try going to bed 2 hours earlier that Ill get rejected.

Very glad to hear this. A lot of people in this group would kill to get 7 or 8 solid hours of sleep.

What's really good to hear is your positive thinking. "I've been doing quite a bit better lately." It is precisely those kind of supportive thoughts that help you sleep better.

Good for you. Keep doing what works.

I haven't tried it, but I've read or heard somewhere that if you do it gradually, you can train yourself to sleep earlier. So if you're currently going to bed around 2 and want to do 12 instead, try sleeping slightly earlier each night. The way you set up your "schedule" is probably best made by you. But maybe if you start off with 15 minutes or something, and keep doing that until it feels like routine, and then do another 15 minutes earlier, you'll be able to get there.

It's probably something I should try for myself, too. I was up until 4:30 this morning. Totally ruins the day.

regarding the pineal gland secreting melatonin in the absence of light: that might explain why i have trouble getting tired when i am looking at a bright computer screen frequently.

Waking up a few minutes earlier each morning for a week or so might be easier to do than trying to force yourself to fall asleep a few minutes earlier each night. Because falling asleep is essentially a passive event, focus on the morning get-up time. Getting a good dose of sunlight soon after waking, and then winding down light and activity as the sun goes down, can help you become sleepier earlier in the evening.

Probably will be a significant challenge to shift your schedule earlier (aka, advancing your sleep phase) if you have always had "owl" tendencies. For good sleep health, try to get enough sleep whenever you can, consolidating as much of it as possible to night.

Good luck, and try not to make any big rapid shifts in sleep schedule.

Harp

Don't know about you guys but I have to drink lots of coffee to stay up to watch movies. Otherwise I just fall a sleep in front of the tv with my beer.