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.

    代替了每天能感覺到的新鮮活力，Jesse Wu 在沉睡了12個小時后醒來。

    許多人會告訴你，他們睡眠質量不好，或者他們在周末睡很長的時間。在周末更多的睡覺并不代表，他們就睡的多好。但是原因究竟是什么，還沒有人確定。

    許多年來，醫生們一直在警告瞌睡帶來的災難-交通事故，肥胖，免疫力下降，但是多余的睡眠并沒有起到多大的幫助。并沒有醫學證據顯示，人們增加睡眠時間，就可以改變他們的生活習慣。Kripke說。

    在這個星期天，增加足夠的睡眠？

    許多工作人員在工作日里睡眠及少（包括在5個小時之內）然后他們通常會在星期天補回來，在星期天花上8到12個小時睡覺，但在他們經過長時間的睡眠之后，他們會感覺更加疲倦。

    這就被稱為睡眠醉酒癥，當一個人經常在睡眠和勞累中徘徊的時候，就會產生如此疾病。有一個案例，一個病人被他的妻子送來急救病房，醫生查出他是應為睡眠醉酒癥而引發的中風。

    專家說，經常睡過頭的表現，可能是疾病的預兆。

    但是如果你有過多睡眠的習慣，這可能是隱藏的健康問題。這可能會縮短你的生命。

    2007年芬蘭科學家發現，20%的睡眠高于8個小時的有生命危險，在同一年，英國科學家發現，睡眠少于5個小時的人的生命危險要比睡覺多于8個小時的人群，有生命危險可能性正在增加，另一項科學顯示日常睡眠多于8個小時的人群更容易得中風。

    科學家說睡眠和長壽在一些時段里是有聯系的，但因素卻是混淆的。

    可能有很多原因引起多過的睡眠，被稱為睡眠過度。

    問題：差的睡眠質量。

    一個人可以睡足夠長的時間，但是仍然感覺很累，是因為他們的睡眠質量不好。

    睡眠周期通常在90分鐘左右。這分為第1階段，輕度睡眠，和過渡睡眠以及深度睡眠。分為4個步驟，然后就唏噓快速眼球轉動（REM）當一個人做夢的時候。

    問題：其他身體問題。

    睡眠呼吸暫停， 窒息都是主要的問題，也就是說在睡眠的時候突然停止一段時間的呼吸。

    通常這些問題都是周期性的，經常在睡眠的時候引起痙攣和抽搐。同樣睡眠過多也可能引起精神不佳。