Salam,
As a medical student, I'm sure all of us are very concern about time.. How much of our time we spend to study?? Never wanted to waste our precious time.. However, only few of us really pay attention on how we spend our resting time when we're off the book, and in this particular case, how do we sleep~
Whether we realise it or not, a good sleeping posture will
give our body a full rest, and a bad sleeping posture may cause strain to our body. In the end, bad sleeping posture will only give us headache and stiff neck, not to mention give us more stress and affecting our performance daily..
Therefore, these are the tips that I manage to find for a good sleeping posture..
1. Firm a firm mattress

This kind of mattress will help to support our back and hold our spine.

Although waterbed may look comfy, it may not give much benefit.
2. Don't sleep with face-down posture

Although it seems cute,
it is actually the worst position ever, because it let our lower back sink deeper,
and may cause swayback (lordosis).
3. Sleeping with pillow
A pillow is very important to support our neck and head, preventing strain.

An example of a good pillow is tempurpedic pillow.

Place a small-medium size pillow between legs to allign the curve of the spine.
Or rolled a towel to replace it.

Again, but not a good example of using the pillow~ ;p
4. Last but not least, mind your SLEEPING TIME~!
Accoring to researchers:
- Babies sleep for about 17 hours each day.
- Older children only need 9 or 10 hours a night.
- Most adults need around 7-8 hours sleep each night.
If you are lack of sleep, it will affect your daily activity.
Sleep-deprived brain will not function well, increase stress level,
more susceptible to diseases and worse, will accelerate the aging process.
I'm sure nobody in their 20's want to look 40's~ :D

Sleeping accordingly will keep your youth-looking face~ ;)
IF~! you don't have enough sleep, you might end up like this little fellow. Please enjoy the video~ :D
That's all folk~
See ya~