The England camp told reporters the skipper was exhausted after batting.
He was also asleep at the moment James Anderson and Tom Curran attempted to delay Australia's celebration.
Australia has been accused of taking its Ashes celebrations too far, after rubbing England's noses in the 4-0 series humiliation.
Australia's back drop for the presentations on the SCG included a giant blue hand holding up four fingers covered with the Aussie flag.
The back drop also included a closed fist covered in England's flag holding up no fingers.
The planned presentation podium didn't do England justice, in the eyes of many commentators who believe the dais scenery crossed the line.
Aussie captain Smith and his teammates appeared not to notice as they celebrated with the presentation urn in front of the cameras.
It was the moment the urn returned for the first time since 2013-14 Ashes series, but the moment has been sullied somewhat by the controversial back drop.
The Aussies didn't seem to care.
The Cricket Australia event management team reportedly arrived in Sydney prepared for every possible outcome — and appeared ready to dress up the stage with a different scoreline if England had been able to get on the scoreboard at the SCG.
Instead the series finished 4-0, and we may never know what becomes of the 3-1 scoreline hands.
Cummins named man of the match
Pat Cummins' eight wickets across two innings has seen him named man of the match for the Fifth Test.
He was given the honour ahead of Aussie batsmen Usman Khawaja (171 runs) and Shaun Marsh (156 runs).
Cummins also finished as the series' leading wicket-taker with 23 scalps across the five-tests.
2.15pm
Australia completes 4-0
Josh Hazlewood got James Anderson nicking off to complete Australia's 4-0 series annihilation.
Anderson fell while trying to defend a shortish Hazlewood delivery on the back foot, but snicked through to keeper Tim Paine for two from 23 balls.
1.25pm
Cummins smashes open the tail with double blow
Pat Cummins broke open the English tail after dismissing Jonny Bairstow for 38 — and then bounced out Stuart Broad two deliveries later.
Cummins got his second and third wickets of the innings in the space of two balls, taking his haul to eight wickets for the test.
3.20pm
Root retires again
Joe Root did not resume his innings after the lunch break.
Root appeared to struggle during the first session of play, regularly calling for water to be brought out to him in the middle as he continued to deal with his stomach bug symptoms.
Tom Curran came to the middle in his place.
2.25pm
Bancroft needs new helmet after nasty blow
Cameron Bancroft needed to be seen by the Australian team doctor after taking a heavy blow to the helmet when fielding at short leg.
Joe Root rocked onto the back foot and smashed a pull shot straight at Bancroft with such speed the Aussie fielder did not even have time to try and defend himself or take any reflex action.
Replays showed the ball hit Bancroft on the side of the grill and then deflected into his shoulder.
The Aussie team doctor came out to speak to Bancroft, but he was allowed to play on after being handed a new helmet.
Joe Root's 'extraordinary' diagnosis
Joe Root's 'extraordinary' diagnosis
England Cricket has said captain Joe Root did not suffer dehydration as first reported and was taken to hospital for a viral gastroenteritis bug.
It came just a few hours after England Cricket reported their skipper had suffered severe dehydration.
The changed diagnosis has been labelled an "extraordinary revelation" from the England camp.
Earlier, England revealed Root would bat on day five, but his arrival at the ground could not be confirmed because of the uncertainty surrounding his hospitalisation.
Aussie Test legend Glenn McGrath told the BBC he believes Root's bug is similar to the one that struck the Aussie camp during the Boxing Day Test.
In Melbourne, Steve Smith had to spend time off the ground and quick Pat Cummins spent sessions sleeping at the MCG while trying to manage his virus.
Root walks out to standing ovation
The SCG crowd gave struggling England captain Joe Root a standing ovation as he walked out to bat.
The England skipper had only arrived at the ground one hour earlier after spending the morning in hospital.
England Cricket said on the morning of day five Root had been taken to hospital to be treated for severe dehydration.
Earlier reports on day five claimed the England skipper had been up most of the night vomitting after spending almost the entire day out in the middle as the temperatures reached 57C in the middle of the ground.
Read more: Shaun Marsh left with burnt arms due to sunscreen superstition
11.35am
Lyon gets Ali for the seventh time
Nathan Lyon equalled the record for the most dismissals of one batsman in a series when he trapped Moeen Ali in front for 13.
Lyon's delivery, bowling over the wicket, slid onto Ali's front pad and was given out after a short pause by the on-field umpire.
It left England 5/121.
