Mr Somers said the "hopelessness" of being on the streets was draining.
"People come home stressed from work and drink half a bottle of wine, so imagine someone who has the stress of being homeless and helpless," he added.
He said the treatment of drug and alcohol addiction had fallen "through a hole" at a time when the use of ketamine or new psychoactive substances such as Spice had "gone through the roof".
Mr Somers is calling for every community to have a fully staffed hostel service, with drug and alcohol workers and psychiatrists who could refer people to a rehab unit.
"Rehab gets about 25% of people clean," he said. "If you had 100 people go that is 25 of them out of the system. That requires a massive financial investment.
"I'm extremely pessimistic about the situation. I can see it reaching a crisis situation."
Caroline Bernard, the head of policy at Homeless Link, which acts on behalf of organisations working with homeless people in England, said there was a need for "clever solutions".
"Cuts in funding for mainstream services mean people are ending up in A&E," she said.
A government spokeswoman said it had a "strong track record" on public health and prevention, with drug and alcohol abuse falling.
She added that local authorities were set to receive £16bn over the current spending period to reduce health inequalities.
The government says it is committed to halving rough sleeping by 2020 and eliminating it by 2027.
"We are investing £550m to 2020 to address the issue," the spokeswoman added.
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