1.Poor quality of sleep 睡眠质量差
It doesn't matter how long you sleep for if you're it's low-quality rest; you'll just wake up tired. Poor-quality sleep can be caused by factors such as sleeping with a pet, drinking caffeinated beverages late in the day, or having too much noise in the background。
无论你睡了多长时间，如果睡眠的质量很差的话，那么你起来后还是会觉得疲累的。造成睡眠质量差的原因有很多，比如抱着宠物一起睡，在临睡前喝了太多含咖啡因的饮料，睡眠时有太多杂音等。
2.Waking up in the wrong phase 起床的时间不对
Your sleep is split into cycles, and you might've woken up during the non-REM stage, which is a state of very deep sleep. Try to shoot for waking up during a REM phase, because then your body will be better prepared to wake up。
睡眠也是有不同周期的。如果你在非快速眼动阶段(non-REM stage)，即深睡眠时期醒过来，那么就会觉得好像没睡醒一样。所以，要尽量在快速眼动睡眠(REM)阶段醒过来，这样你就能为起床做好更充分的准备。
3.Medication hangover 药物副作用
The effects of certain medications that cause drowsiness can linger until the next morning. Check with your doctor to see if you can adjust the dosage or change medications。
有些药物的副作用会使你在第二天早上仍然感到昏昏沉沉想睡觉。这时，你应该和医生商量一下，看看能不能调整一下药物的剂量或者换一种药。
4.Medical condition 身体状况
Certain medical conditions like sleep apnea can disrupt your night's rest. Disorders like depression can also cause you feel drained of energy, a symptom that can contribute to your grogginess。
有些身体状况也会让人睡不好，比如睡眠呼吸窒息。抑郁也会使人精神不济，表现出来的症状就是萎靡不振。
5.Your body clock is not in sync 生物钟不协调
If you've been keeping an erratic sleep schedule, then your body will probably need time to adjust to waking up at a certain time during the morning. Try to make a more regular schedule, and you'll probably see a difference in how you feel in the morning。
如果你的作息时间紊乱，那么你的身体在早晨起床的时候就会需要时间来做出调整。试着保持一个规律的作息时间，你会发现早上起床将会有大大的不同。
