I've done that when between live-in GFs.
So, not lately ... but a lot of experience with it. Depending upon the amount of tension, you can go for several hours. The 2 lbs exertible by the
penimaster type of devices can go for hours. I wouldn't go more than three without a break. Definitely set an alarm clock to wake you so you can take it off. All night could be dangerous. The upside of this is that if you're seriously weight training working out you should wake in the middle of the night anyway to eat again. I sleep about six hours so an alarm after three to take off the device and go eat was perfect.
The
penimaster style of strap (while perhaps one of the better thought-out designs) will come loose the first time you get wood, a loop style or vac style are better for sleeping. The clamp/vice style like the autoextender encourages one to use too much force for any unmonitored sessions. Be careful sleeping in those that you don't use way too much tension.
If you're going over 5 lbs, don't sleep in it. ( IMO ). It's more dangerous. More doesn't equal better when you're unconscious and not paying attention, it equals potential cell death. If you wouldn't do it while you're awake, don't do it while asleep. You know you take breaks when awake. They're even more important when there's no active monitoring.
At first you might be awakened by soreness when you've had enough. Stop there even if it's short of a particular time goal.
After you get used to it, waking up from soreness might not happen anymore, so an alarm clock as a safety factor is critical.
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