Sleep systems

Case studies

Our Sleep Systems framework details how bags can be layered together and/or combined with clothing, but while different systems may have similar ratings to each other, sleeping comfortably isn’t simply a matter of numbers! So, in these case studies, we share some of the human experiences taken from development testing and from real-world use, so you can get a feel for different styles of Sleep System. As always, do feel free to contact us by phone or email if there’s anything you need to discuss.
Pete Elliott on Snowden, 3°C

Pete Elliott on Snowden, 3°C

"Slept well until around 3:00am. Then awake and cold. Trying to work out why - I realized my head was cold. No hood on the jacket. No hat in the tent. Lesson - remember to insulate the head as well."
Arran, Scotland, 2°C

Arran, Scotland, 2°C

"The Wafer gear did its job, inside the sleeping bag as well as out. I slept OK."
Cold Store, -21°C

Cold Store, -21°C

"With ultralight down clothing inside a -5°C rated bag I was warm enough all night in the -21°C store. But when I had to get out to go to the loo, it felt like a life saver to have the down gear on already."
Pete Elliott in Glen Affric, 1°C

Pete Elliott in Glen Affric, 1°C

"First night just used Minimus bag and was cold. Second night I put the Filler bag inside the Minimus and was toasty. Different experience."
Scottish Winter with Petesy

Scottish Winter with Petesy

"The two bags feel like one, but it’s somehow cosier … I have to say I have been warm, comfortable even delighted using these bags ... I think it's good to look at the two bags as a system and as individual bits of kit."
Ben Kane Top Camp on Broad Peak 8051m, -25/30°C

Ben Kane Top Camp on Broad Peak 8051m, -25/30°C

"When we were on our summit push I used just the Overbag and my Xero suit, which was perfect. Plenty of room for the suit to loft."
Winter Bivvy with Sam Cook

Winter Bivvy with Sam Cook

"I 'bivvied' in the snow on the fell above my house. I was as 'snug as a bug' in the Overbag and down liner (Filler). So much so that I slept until 8am."
Kayaking in Greenland with Sam Cook

Kayaking in Greenland with Sam Cook

"It is a pleasure when you know the temperature is dropping just to slip into another bag and double the warmth factor. This has been achieved mostly with a PHD Overbag and Minimus bag."
Pete Elliott in Yorkshire Dales, 3°C

Pete Elliott in Yorkshire Dales, 3°C

A case study showing the importance of insulating your legs when you use a sleep system.
Cold Store, -21°C

Cold Store, -21°C

"Pete was using a Hispar 500 (rated to -15°C). I was in a Minim Overbag (rated to –5°C) with an Ultra Vest and Minimus Down Trousers and Socks. I was warm enough to sleep and so was Pete. The temperature varied between -18°C & -21°C all night."
Kayaking in Greenland with Martin Rickard

Kayaking in Greenland with Martin Rickard

"Applying the layering principle to sleeping bags makes as much sense as it does for clothing. So, this past summer used the PHD Minimus and PHD Minim Overbag sleeping bags. Immediately the benefits became obvious."
Arran, Scotland, 2°C

Arran, Scotland, 2°C

"The Wafers showed their real value when I had to get up in the early hours and walk the dog around in a wind chill of about -6°C ... Besides adding warmth inside the sleeping bag, they really proved the comfort value of having warm clothing on already."
Scottish Winter with Petesy

Scottish Winter with Petesy

"The two bags feel like one, but it's somehow cosier. I have been warm, comfortable even delighted using these bags. I think it's good to look at the two bags as a system and as individual bits of kit. That way it does kinda cover the whole year."
Sam Cook on Layering

Sam Cook on Layering

"I have a long held belief in the 'layering principle' extending into our sleeping quarters and this is where PHD have developed a modern approach with their sleep systems to suit a multitude of adventure activity situations."
Ben Kane on Broad Peak 8051m, -20°C

Ben Kane on Broad Peak 8051m, -20°C

"As for the sleeping bags, I was blown away at how well the Hispar Overbag works. I used it with my Hispar 500 above base camp and it was simply too warm, but great to have just in case."
Kayaking in Greenland with Martin Rickard

Kayaking in Greenland with Martin Rickard

"Two smaller bags took up about the same space as my old bag, but were considerably easier to pack … I was very impressed with the system. It’s now so obvious - I can't believe it's taken me 30 years to apply this layering principle to my sleeping system."