Well, consider how N works:
"It depresses brain function so the patient stops breathing and dies."
Yes, your body would be deprived of oxygen and the damage to brain and other organs would be severe
if you survived an OD.
However, "survive" can very well mean that you'll die from eventual organ failure a few days later and you likely never regained consciousness.
If the amount of N taken is so little (as in 1 tsp) that you "just sleep for 24 hrs" I can tell you that physical damage can occur in form of "compartment syndrome".
Example (own experience):
OD of benzoes, morphine.
Sidesleeper, turns on the right. Goes into a long sleep and brain doesn't recognize that right arm is tingling from reduced blood flow. Most people would roll over on back or left side.
But OD is preventing it. Brain is slow. Person is so deep asleep the natural instinct is suppressed.
(This also happens often to seniors who have a stroke, fall, can't move and aren't found for a day or two.)
Ends up in hospital with a MASSIVELY swollen upper arm and shoulder. Muscle fibres died off, kidney values extremely elevated (from the protein of muscle fibres flooding the kidneys to be flushed out). 3-4 days of high volume IV fluids to bring kidney levels down.
Months of arm/shoulder pain and restricted movement. Still not back to full function 2 yrs later.
Not. Fun.
en.m.wikipedia.org