Sleep Less, Live More

First author Daniel F. Kripke, M.D., a UCSD professor of psychiatry who specializes in sleep research, said “we don’t know if long sleep periods lead to death. Additional studies are needed to determine if setting your alarm clock earlier will actually improve your health.”

But, he added “individuals who now average 6.5 hours of sleep a night, can be reassured that this is a safe amount of sleep. From a health standpoint, there is no reason to sleep longer.”

This study doesn't constitute scientific evidence that can actually tell anyone how much to sleep because there is no control group and no experimental group. It can't possably take into account many factors, such as the fact that people who are dying tend to sleep more. This is really more of a "we need to study this more" kind of study.

We have known for a long time that sleeping too little or too much is associated with higher mortality rates. (Note "associated", not "a cause of"). This study just indicates that 6 hours of sleep isn't significantly worse than 8 hours of sleep. No previous study has been able to make that distinction because their data sets were too small.

The lesson that we can take from it is that we probably don't need as much sleep as we previously thought. If you want a concrete guideline for how much you should sleep, there are more important factors than your clock to consider. How long after you wake up do you still feel tired? Does a lack of sleep or a lack of time lead to greater stress in your life? (Reducing stress is proven very concretely to improve health)

The actual optimum amount of sleep varies with age, life style, diet, and countless other factors, which is why we are only now able to quantify the average within an hour.

There are some basic tests that you can perform. They are all highly subjective and not particularly accurate, but could still be usefull.

1. How long do you feel tired after you wake up?

If its longer than 2 hours, then there is a problem, but more sleep might not be the solution. Insufficient physical activity, uncomfortable or unproductive sleep, and breathing problems can also cause the same affect..

2. How good are you at math? Roughly 1-3 hours after waking up is the best time for concret analysis and spacial reasoning. The difference is tangible for most people. You shouldn't need any elaborite testing methods to notice a difference. Just try reading a text book. If it is easier after 5 hours of being awake than it is after 1 1/2 hours, then you probably aren't getting enough sleep. If it is roughly the same difficulty regardless of when you do it, then you may be getting too much sleep. I should mention that not everyone can notice a difference, so don't reduce the ammount of sleep you get based on this. It is a much better indicator of not enough sleep than too much.

3. Are you tired during the day? Other than when bored, do you feel exhausted, short tempered, or easily agitated? Too much or too little sleep can cause any of these symptoms, but not necessarily the same ones. It varies from person to person, so your personal experience is the best way to read middle of the day indicators.

For me, for example, too much sleep makes me feel sleepy all day. Physical excitement reduces the affect. Not enough sleep mostly affects my concentration and self control, but I usually don't feel sleepy.

4. How sharp are your sleep cycles? Insuficient sleep leades to sharp changes in state, shortened rem periods, and longer n3 and n4 periods. Too much sleep leades to the opposite, extended n1 and n2 periods, particularly noticable in the middle of the night.

You don't need an EEG to notice the difference.

n1 most closely resembles wakefullness, but is usually described as "hazy". You normally enter this state when you first go to sleep, but if you have been sleeping too much, you are likely to wake after a rem cycle. Even if you don't remember being awake, you are more likely to remember an n1 phase. Dreams are rare during n1, and usually feel like you are floating, but lack sensory realism. Conscious thought can exist, but are often muddled. During n1, you may think that you are awake. You are also likely to remember several disjointed dreams when you habitually sleep too much.

On the other end of the spectrum, n3 and n4 can be pretty distinctive, too. Physical paralysis is one indication. During n4, the motor strip is innactive, meaning that your brain is physically unable to make your body move. It is possible to dream during n3 and n4, and the dreams are rather distinctive. They are vague (or at least are remembered as being vague), and often very scarry. Waking up suddenly from n3 or n4 often leaves you immobile for several minutes. Waking from an extend n3 or n4 (particularly n4) usually feels cold and/or numb. Tingling sensations early in the morning, and taking more than a few minutes to regain motor control are signs of spending a lot of time in n4.

If my descriptions don't ring any bells with you, there are other ways to learn how the different stages of the sleep cycle feel to you. Forcing yourself to take a nap in the middle of the day causes you to spend a lot of time in n1 and rem. Falling asleep with alcohol poisoning, and extreem physical exhaustion, cause extended n4 stages. Also, waking from n4 often carries sleep inertia with it. Ever sleep for 2 hours, then jump out of bed like you were on springs? The process of leaving n4 is largely hormonal, and insufficient sleep can cause your body to over react. Waking in such a fashion isn't necessarily proof of insufficient sleep, but when it is acompanied by lack of fine motor control, particularly if the burst of energy is short lived, is a very good indicator.

5. What time of day do you sleep?

The effectiveness of sleep is greatly improved by sleeping when your body needs it, as opposed to when your clock wants it. The best time to sleep is when your melatonin levels are the highest and when your body temperature is the lowest. Fortunately, your body adjusts its rhythms to match your sleeping cycle, but sometimes other factors are greater. If you are sleeping at a time other than the time that it is easiest for you to go to sleep, then more sleep will be required. It is also important to mention, especially in the context of youth, that your daily rhythm changes naturally, especially during times of growth, and may be considerably longer than 24 hours. Changes in lighting and ambient temperature have some very big affects.

6. How easily can you fall asleep during the day? If boredom doesn't make you sleepy then you are getting too much sleep. Not enough sleep is a bit harder to pinpoint. Even if you have trouble taking naps during the day, your body might still give some of the signs of wanting a nap, such as increased melatonin levels and decreased body temperature. If you start to get nostalgic or weepy when you are bored, or if you feel suddenly cold after being physically innactive, then your body is asking for a nap.

Mileage for each test will vary from person to person. The best one for me is #2, the math test. When I get really out of whack, #4 is a really good indicator. My results are directly related to my life experiences, though.

Thats the long answer. The short answer is that while this study didn't deal with anyone under 30, the same basic observations have been made. Most of the previous studies indicate that adolescents need about 2 hours more than adults, and that the difference is coupled with growth rate. Most of the previous work focused on attention rather than mortality, though. How much you sleep doesn't have as much affect on your health and development as what you do when you are awake, so don't approach sleep like a fad diet or a religous ideology. Healthy living is too personal to accurately quantify.