Calling sleep many times in bash takes one process per time you sleep. Not anymore!

sleep.sh

#!/bin/bash
# 20191016 Robert Martin-Legene
# CC0

# Make us a directory just for this pipe
sleepdir=$( mktemp -d )

# Remember to clean up when we're done
tailpid=
trap 'test -n "${tailpid}" && kill ${tailpid} ; rm -rf ${sleepdir}' EXIT

# File name of the actual pipe
pipe="${sleepdir}/boringpipe"

# Create a FIFO pipe
mknod "${pipe}" p

# read(1) hangs in open(2) until there is a
# program already connected to the other end.
tail -fs 3600 /dev/null > "${pipe}" &
tailpid=$!

sleep() {
	# Don't let read(1) overwrite data in the main program
	local REPLY
	read -t $1 < $pipe
}

sleep 1