Does it matter which 7 hours I sleep?
May 6, 2014 5:30 AM   Subscribe

I've noticed that when I sleep from, say, 11-6 as opposed to 12-7, I feel very different upon waking up. Even just shifting everything one hour late, when I get up at 7 my mornings are pleasant and alert. If I wake up at 6, even if I had gone to bed and fell asleep at 11, I had to take a nap somewhere in there. Are there studies that shows which hours you sleep actually matter? Or are all of this in my head?
posted by redwaterman to Health & Fitness (7 answers total) 15 users marked this as a favorite
This may interest you. I'd say it's not all in your head.
posted by whoiam at 5:39 AM on May 6, 2014 [1 favorite]

It could have something to do with the time of sunrise where you live. If it's still dark at 6 (as it is here where I live) but light at 7 your body may just like the light.
posted by mareli at 5:49 AM on May 6, 2014

The sunrise thing is big (I'm waking at 6 whether I like it or not right now), plus if you USUALLY sleep until 6, when you sleep until 7 you're effectively timeshifting yourself to a longer day, which is pleasant (this is why East-to-West jetlag is less horrible than West-to-East jetlag). So it might be that if you did start getting up at 7 every day, eventually you'd settle back into the new normal and then you'd find that waking up at 8 felt better.

Sleep cycle is also connected to digestion So it might be that if you shifted your dinner an hour earlier, you'd feel better about sleeping 11-6. Or it might even be that when you go to bed at 12, you might start your wind-down routine at about the same time as you do when you go to bed at 11, so that you effectively get more rest time.

I don't think it's all in your head, except insofar as most of the stuff that's to do with your sleep cycle is, in fact, in your head. If you can sleep 12-7 and you like it, go for it! If you really need to wake up at 6 there are a lot of things you can do to make it easier - I used to love my dawn simulator alarm clock when I had to be at work at 7.
posted by mskyle at 6:35 AM on May 6, 2014 [1 favorite]

I have no idea if this has any scientific basis or not, but I am the exact same way. My mind draws this bright line at 7am, and anytime I wake up before that I feel slightly off for the rest of the day, even if I got enough sleep. It's not enough of a difference to really interfere with anything, but it's noticeable (at least to me).
posted by breakin' the law at 7:42 AM on May 6, 2014 [1 favorite]

Not in your head. I did research on this for an article ~15 years ago or so, and although my memory might not get all of the details exactly right, the basic facts haven't changed.

Your circadian rhythm is basically like a sine wave. It has a zenith, the spot when you're most awake and alert, and a nadir, which is the low point at which you ideally will be deep in REM sleep. It depends on the person, but that zenith and nadir each correspond to a pretty specific time of day. How rested you feel depends largely on how your sleep patterns match up with your circadian rhythm. If your hypothetical nadir is at 5:00 am, and you're getting up at 6:00, you're going to feel piss-poor. If it's at 3:00 a.m., and you're getting up at 6:00, you will feel comparatively much better.

There are certain factors -- zeitgeibers! -- that can shift that zenith/nadir forward or backward on the clock. Light is a big one, and light therapy has proven to be very beneficial to people who work night shifts, for example.

You want to read up on the work of Charles Czeisler for all the nitty-gritty, sciency details regarding circadian rhythms and sleep patterns.
posted by mudpuppie at 8:57 AM on May 6, 2014 [6 favorites]

It's not "all in your head". The body has a natural circadian rhythm and one aspect of that regulates your sleep/wake cycle through the production of the hormones melatonin and cortisol. I'm sure that it's possible the circadian rhythm of your body may involve even more than melatonin and cortisol or that we will find in the future that it involves more but for the time being we can say very much that your sleep cycle is being regulated by melatonin and cortisol. Any even simple book on sleep or on circadian rhythms will go tons into this, by the way, as it's essential stuff.

I have heard that the best, "most restorative" sleep occurs between 10 pm and 2 am. This is because between these hours it is most "natural" for you to be sleeping. Your melatonin levels should be peaking and your cortisol should be low ( I think highest melatonin is about 2am and lowest cortisol is about 4 am). However, just as important, is that these are AVERAGE cycles that I am talking about. Your particular circadian rhythms may differ slightly in one direction or the other, and your cycles (as everybody's) are highly regulated and influenced by signals from outside your body. For example, day light, blue light from computers, indoor lighting, phones ( blue light mimics the effect of daylight), eating, exercising, etc. Melatonin makes you feel sleepy by the way, and cortisol makes you feel alert. Generally the body starts kicking up the production of melatonin around 9pm (after the sun goes down) and increasing it from then on. However this natural increase in melatonin production is often stalled/hindered because of all the blue light we get exposed to from computer and phone screens, tvs, indoor LED lighting. It's even impossible to be out in public after 9pm these days without majorly hindering your melatonin production ( all the hallways and laundry room in my building has BRIGHT LED lighting now so I try not to do laundry too late, not to mention all the trains and buses). This reduction of melatonin production and sleep quality has been linked to many other negative processes in the body by the way, if you're inclined as many to think that sleep is relatively inconsequential to health and far less relevant than "diet and exercise". TCM and Ayurveda has, and has had for a very long time, an extremely deep understanding of our sleep and daily cycles/activities to our health and wellbeing, and how our "sleep and daily cycles/activites" are always related to "nature" and the environment. Ayurveda in particular, for thousands of years, has placed a HUGE emphasis on not only sleep patterns, but on eating, meditating, exercising, any possible kind of activity whatsoever, and the time of day and season at which these activities are performed. And just one example of the current research in circadian rhythms, is that your body behaves very differently when you eat something depending on the time of day -- if you eat a meal at say 1 am rather than 12 noon your body deals with it in a much hindered way, less insulin is produced for example.

So I very much believe you that you may feel quite different with even a one hour shift in your sleep cycle. It also seems possible that when you wake up at 6 am your cortisol has not kicked in enough (and/or there is not enough daylight at that time which also triggers your cortisol), and there is a lingering "grogginess" from waking up that way that makes you need a nap later on. I feel much, much more well rested if I sleep from 12am to 9am than 3 am to noon, but it actually took me years to notice that because I was so much in the habit of sleeping late every single night. What a difference just shifting things a few hours makes!
posted by Blitz at 1:52 PM on May 6, 2014

This sounds like me. I think it's a night owl thing that the later you're going to bed and the later you're sleeping "in," the better you feel.
posted by jenfullmoon at 3:37 PM on May 6, 2014

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