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By making a call to function :
thread_switch(S_SLEEP /*State*/, wchan *wc /*wait channel*/)

This would put curthread inside the kernel to sleep by putting it on sleep queue and changing its state from runnable to sleep.

wait_queue_timeout are best way to to sleep inside kernel

why do we need sleep in the kernel?
Kernel is like a machine which run everything , if kernel sleep , other thread won't get a chance to run , so the whole system will stop , unless you want to process interrupt.

I guess if in kernel you want this thread to sleep, you can do a context switch to let the current thread sleep, then you can let other thread run.

if you really want to sleep in kernel, you can disable interrupt, so that the scheduler won't have a chance to work , you will be able to sleep as long as you want with a while loop.

why not use schedule with a timer

In atomic context use udelay/mdelay/ndelay(unsigned long val) functions
in non atomic context use waitque or usleep_range(), msleep() functions

Through jiffies
for e.g :- n*HZ where n may be 1,2,3,... as per requirement.