I fall asleep during the day. I’ve tried getting more hours of sleep at night
and it doesn’t solve the problem. When I’m bored or confused, my
body says “Naptime!” It can be quite embarrassing.
There are two primary things that determine your alertness (or drowsiness) during day-time: sleep debt and circadian phase. The more sleep debt you have, the more tired you feel during the day. If you have significant amounts of sleep debt it might take weeks to decrease the sleep debt to normal levels.
Then you have circadian alerting, which makes everyone with normal sleep schedule more tired in the afternoon. The desire for afternoon naps is based on our biology. That said, the (afternoon) drowsiness is much exaggerated by the amount of sleep debt you have. With unusually large sleep debt, you might find it almost impossible to stay awake at some point in the afternoon.
Circadian alerting starts to kick in again in the evening. In fact, most people are at their peak alertness only couple of hours before their bedtime.
Sleep debt seems to be strictly cumulative (ie. all the sleep debt you accumulate have to be paid back), but it takes considerable amount of time to pay it back, because you can’t pay the debt back in one go. Something like 9-10 hours a night seems like the most efficient amount. Depending on the accumulated amount of debt, the daily sleep need should start to stabilize after some days or weeks. Eventually you should sleep exactly the amount of sleep debt that you acquire during in between waking and sleeping.
Unfortunately, decreasing the sleep debt to exactly zero is not optimal for anyone who has to adjust to other people’s schedules. This is because our circadian cycle isn’t exactly 24 hours. Most often it’s something like 24,5 to 25 hours. This means that if you were to maintain zero sleep debt (other than the debt you accumulate during the next day before you sleep again), your sleep time will start to shift 0,5 to 1 hour per day. If this sort of shift doesn’t cause practical problems, I’d suggest to try it out. You go to sleep whenever you feel tired, and wake when you don’t feel tired anymore. (See this article for more information: http://www.supermemo.com/articles/sleep.htm)
Summa summarum: if you feel genuinely tired during the day, it means you have too much sleep debt and the only way to increase alertness is to sleep more. (Unless you have a specific sleep disorder, which needs to be fixed first.)
One thing I always forget to mention: when you start sleeping more, you will probably notice that you feel drowsier during daytime for a while. If you consistently sleep more, the drowsiness will wear off. But this is why many people complain about “sleeping too much” or not becoming alert after sleeping exceptionally long. It’s your brain’s way of saying you should sleep more.
I haven’t seen any good explanations for this effect, but I think it’s simply to get yourself more “hungry” of sleep when you do have time for it.
There are two primary things that determine your alertness (or drowsiness) during day-time: sleep debt and circadian phase. The more sleep debt you have, the more tired you feel during the day. If you have significant amounts of sleep debt it might take weeks to decrease the sleep debt to normal levels.
Then you have circadian alerting, which makes everyone with normal sleep schedule more tired in the afternoon. The desire for afternoon naps is based on our biology. That said, the (afternoon) drowsiness is much exaggerated by the amount of sleep debt you have. With unusually large sleep debt, you might find it almost impossible to stay awake at some point in the afternoon.
Circadian alerting starts to kick in again in the evening. In fact, most people are at their peak alertness only couple of hours before their bedtime.
See this graph for explanation of circadian phases: http://www.ride4ever.org/images/normalsleep.gif (the full article: http://www.ride4ever.org/news/fatigue.php).
Sleep debt seems to be strictly cumulative (ie. all the sleep debt you accumulate have to be paid back), but it takes considerable amount of time to pay it back, because you can’t pay the debt back in one go. Something like 9-10 hours a night seems like the most efficient amount. Depending on the accumulated amount of debt, the daily sleep need should start to stabilize after some days or weeks. Eventually you should sleep exactly the amount of sleep debt that you acquire during in between waking and sleeping.
Unfortunately, decreasing the sleep debt to exactly zero is not optimal for anyone who has to adjust to other people’s schedules. This is because our circadian cycle isn’t exactly 24 hours. Most often it’s something like 24,5 to 25 hours. This means that if you were to maintain zero sleep debt (other than the debt you accumulate during the next day before you sleep again), your sleep time will start to shift 0,5 to 1 hour per day. If this sort of shift doesn’t cause practical problems, I’d suggest to try it out. You go to sleep whenever you feel tired, and wake when you don’t feel tired anymore. (See this article for more information: http://www.supermemo.com/articles/sleep.htm)
Summa summarum: if you feel genuinely tired during the day, it means you have too much sleep debt and the only way to increase alertness is to sleep more. (Unless you have a specific sleep disorder, which needs to be fixed first.)
One thing I always forget to mention: when you start sleeping more, you will probably notice that you feel drowsier during daytime for a while. If you consistently sleep more, the drowsiness will wear off. But this is why many people complain about “sleeping too much” or not becoming alert after sleeping exceptionally long. It’s your brain’s way of saying you should sleep more.
I haven’t seen any good explanations for this effect, but I think it’s simply to get yourself more “hungry” of sleep when you do have time for it.