Instead of feeling crisp and refreshed, Jesse Wu wakes up sluggish after 12 hours of sleep.

    Many people will tell you, they sleep a little worse when they sleep a long time on weekends. Too much long sleep on weekends does not seem to make people feel better. But the reasons haven't been determined.

    For years, doctors have warned about the dangers of not getting enough shuteye -- traffic accidents, weight gain, decreased productivity and immune protection, but the effects of oversleeping are not well-understood. There isn't medical evidence to recommend that people who sleep long hours should change their habits, Kripke said.

    Daylight saving time ends this Sunday, giving sleepers a bonus hour of sleep.

    Many professionals sleep little on the weekdays （about five hours） and make up for it on weekends, spending eight to 12 hours blissfully hibernating. Sometimes, after a long stretch, they wake up too tired to function.

    This is known as sleep drunkenness, when a person hovers between sleep and wakefulness. In one case, a patient who had sleep drunkenness came to the emergency room because his wife thought he had a stroke.

    Oversleeping once in a while doesn't present serious health risks, experts say.

    But if you habitually sleep excessively, it could be the result of an underlying health problem. And it could be cutting into your life span.

    A 2007 Finnish study found that the mortality risks increased by about 20 percent for people who slept more than eight hours. That same year, a British study found that people who slept five hours or less and those who slept more than eight hours also faced increased risks. Another study showed that people who routinely slept more than eight hours a night had a greater chance of stroke than others with less sleep.

    Scientists say sleep and longevity are somehow associated, but there might be confounding factors.

    Here are possible factors for habitually excessive sleep, known as hypersomnia:

    Problem: Poor-quality sleep

    A person could sleep the recommended amount, but still feel tired because he or she got poor quality sleep.

    The average sleep cycle takes 90 minutes to complete. It starts from stage 1, the lightest sleep, and progresses to deeper levels through stage 4. Then, it continues to rapid eye movement （REM） sleep when the person dreams.

    Problem: Other medical conditions

    Sleep apnea is a major cause of problems, when breathing stops during sleep.

    Another possibility is periodic limb movement disorder, which causes a person to jerk and twitch during sleep, causing disruptions. Depression has also been associated with excessive sleep.

    代替了每天能感觉到的新鲜活力，Jesse Wu 在沉睡了12个小时后醒来。

    许多人会告诉你，他们睡眠质量不好，或者他们在周末睡很长的时间。在周末更多的睡觉并不代表，他们就睡的多好。但是原因究竟是什么，还没有人确定。

    许多年来，医生们一直在警告瞌睡带来的灾难-交通事故，肥胖，免疫力下降，但是多余的睡眠并没有起到多大的帮助。并没有医学证据显示，人们增加睡眠时间，就可以改变他们的生活习惯。Kripke说。

    在这个星期天，增加足够的睡眠？

    许多工作人员在工作日里睡眠及少（包括在5个小时之内）然后他们通常会在星期天补回来，在星期天花上8到12个小时睡觉，但在他们经过长时间的睡眠之后，他们会感觉更加疲倦。

    这就被称为睡眠醉酒症，当一个人经常在睡眠和劳累中徘徊的时候，就会产生如此疾病。有一个案例，一个病人被他的妻子送来急救病房，医生查出他是应为睡眠醉酒症而引发的中风。

    专家说，经常睡过头的表现，可能是疾病的预兆。

    但是如果你有过多睡眠的习惯，这可能是隐藏的健康问题。这可能会缩短你的生命。

    2007年芬兰科学家发现，20%的睡眠高于8个小时的有生命危险，在同一年，英国科学家发现，睡眠少于5个小时的人的生命危险要比睡觉多于8个小时的人群，有生命危险可能性正在增加，另一项科学显示日常睡眠多于8个小时的人群更容易得中风。

    科学家说睡眠和长寿在一些时段里是有联系的，但因素却是混淆的。

    可能有很多原因引起多过的睡眠，被称为睡眠过度。

    问题：差的睡眠质量。

    一个人可以睡足够长的时间，但是仍然感觉很累，是因为他们的睡眠质量不好。

    睡眠周期通常在90分钟左右。这分为第1阶段，轻度睡眠，和过渡睡眠以及深度睡眠。分为4个步骤，然后就唏嘘快速眼球转动（REM）当一个人做梦的时候。

    问题：其他身体问题。

    睡眠呼吸暂停， 窒息都是主要的问题，也就是说在睡眠的时候突然停止一段时间的呼吸。

    通常这些问题都是周期性的，经常在睡眠的时候引起痉挛和抽搐。同样睡眠过多也可能引起精神不佳。