Dr. Axel Gebauer / Red panda (Ailurus fulgens), cub 4 days old in breeding den, captive

Chadden Hunter / Southern elephant seal (Mirounga leonina) close up of sleeping individual, South Georgia. Taken on location for BBC Frozen Planet series, 2008

David Woodfall / Bull Grey Seal (Halichoerus grypus) asleep in pool with reflection of bombing range sign in pool. Donna Nook, UK, November.

David Woodfall / Bull Grey Seal (Halichoerus grypus) asleep in pool with reflection of bombing range sign in pool. Donna Nook, UK, November.

Andy Sands / Dormouse (Muscardinus avellanarius) asleep in old Blackcap nest. Captive. UK, September.

Aflo / ic-02802 Two domestic cats sleeping with heads close together {Felis catus}

Aflo / ic-02801 View of heads of two domestic cats sleeping close together {Felis catus}

Mark Taylor / Two kittens asleep under a scarf.

Staffan Widstrand / Portrait of Walrus {Odobenus rosmaris} asleep on shore, Chukotka, Russia.

Gabriel Rojo / Two Giant armadillos asleep {Priodontes maximus} Argentina, endangered, captive

George McCarthy / Hibernating dormouse {Muscardinus avellanarius} curled up asleep in nest, Sussex, UK

Michael & Patricia Fogden / Brown-throated Three-toed Sloth (Bradypus variegatus) female asleep in Cecropia tree, rainforest, Panama

Jabruson / Mountain gorilla asleep {Gorilla beringei} Virunga NP, Democratic Republic of Congo. "Rafiki" killed by roaming militia after Rwandan crisis.

Doug Perrine / Tawny nurse shark asleep under coral reef ledge {Nebrius ferrugineus} Burma Banks, Thailand, Andaman Sea (Non-ex).

Andrew Cooper / Grey Squirrel babies (Sciurus carolinensis) asleep in drey / nest, Devon, UK

Fiona Rogers / Celebes / Black crested macaque (Macaca nigra) sub-adult male resting on back, Tangkoko National Park, Sulawesi, Indonesia.

Mark Taylor / Black-and-white Border Collie x Cocker Spaniel puppy, 11 weeks old, asleep on a cream teddy bear.

Suzi Eszterhas / Brown throated Three-toed Sloth (Bradypus variegatus) asleep in tree, Aviarios Sloth Sanctuary, Costa Rica (Digitally removed twig in foreground)

Suzi Eszterhas / Brown-throated Three-toed Sloth (Bradypus variegatus) female sleeping in tree, Aviarios Sloth Sanctuary, Costa Rica

Staffan Widstrand / Walrus (Odobenus rosmaris) asleep, Svalbard, Norway

Markus Varesvuo / Long eared Owl (Asio otus) asleep in daytime, Helsinki Finland March

Jabruson / Western lowland gorilla (Gorilla gorilla gorilla) silverback 'Makumba' sleeping after a morning of feeding. 'Makumba' is the leader of the habituated gorilla family that goes by the same name, Bai Hok...

Jabruson / Western lowland gorilla (Gorilla gorilla gorilla) silverback 'Makumba' sleeping after a morning of feeding. 'Makumba' is the leader of the habituated gorilla family that goes by the same name, Bai Hok...

Mark Carwardine / Southern elephant seals asleep on beach {Mirounga leonina} Falkland Is

Mark Carwardine / Southern elephant seal asleep, face portrait {Mirounga leonina} Falkland Is

Loic Poidevin / Short eared owl (Asio flammeus) asleep on branch, Breton Marsh, West France, June

Mark Taylor / Two cute tabby kittens asleep in a hammock.

Mark Taylor / Black and white Border Collie x Cocker Spaniel puppy, 11 weeks, asleep in a wicker basket.

Mark Taylor / Cute tabby kitten, Stanley, 6 weeks, asleep in someone's arms.

Mark Taylor / Cute tabby kitten, Fosset, 5 weeks, asleep under a pink scarf.

Mark Taylor / Black and white Border Collie x Cocker Spaniel puppy, 11 weeks, asleep in a basket.

Mark Taylor / Bichon Frise cross Yorkshire Terrier puppy, 6 weeks, asleep on Netherland Dwarf cross rabbit, Peter.

Mark Taylor / Bichon Frise cross Yorkshire Terrier pups, 6 weeks, asleep in a basket.

Mark Taylor / Bichon Frise x Yorkshire Terrier puppies, 6 weeks, asleep.

Tui De Roy / Common potoo (Nyctibius griseus) at rest, Andean cloud forest, Mindo Valley, Ecuador

Loic Poidevin / Collared scops owl (Otus lettia) Kanha National Park, Madhya Pradesh, India, March

Konrad Wothe / Greater flamingoes (Phoenicopterus ruber) flock asleep standing up, Camargue, France, April

Todd Mintz / Snowy owl (Bubo scandiaca) resting on the Canadian prairie, Saskatchewan, Canada, February

Todd Mintz / Snowy owl (Bubo scandiaca) male resting on northern migration across Canadian prairie, Saskatchewan, Canada, March

Todd Mintz / Coyote (Canis latrans) curled up on snow, resting on the Canadian prairie, Saskatchewan, Canada, February

Todd Mintz / Coyote (Canis latrans) curled up on snow, resting on the Canadian prairie, Saskatchewan, Canada, February

Konrad Wothe / Chimpanzee (Pan troglodytes) male sleeping on ground, Mahale Mountains National Park, Tanzania, East Africa

Ben Hall / Grey seal (Halichoerus grypus) resting on beach at dawn, Lincolnshire, UK December

Ben Hall / Sanderlings (Calidris alba) resting on shoreline, Lincolnshire, UK December

Florian Möllers / Quinling Golden snub nosed monkey (Rhinopitecus roxellana qinlingensis), adult male sitting on a branch, relaxing. Zhouzhi Nature Reserve, Qinling Mountains, Shaanxi, China.

Dr. Axel Gebauer / Stray domestic dogs sleeping in empty sales stall, Darjeeling, West Bengal, India

Dr. Axel Gebauer / Red panda (Ailurus fulgens), sleeping in tree, Darjeeling, West Bengal, India, captive

Dr. Axel Gebauer / Red panda (Ailurus fulgens), sleeping in tree, Darjeeling, India, captive

Brent Stephenson / Leopard Seal (Hydrurga leptonyx) asleep lying on sea ice. Cierva Cove, Antarctic Peninsula, Antarctica, January.

Brent Stephenson / Gentoo Penguin (Pygoscelis papua) asleep, standing on a rock against a blue sky. Neko Harbour, Antarctic Peninsula, Antarctica, January.

Brent Stephenson / Gentoo Penguin (Pygoscelis papua) standing on a rock facing another bird lying down asleep on its nest site. Neko Harbour, Antarctic Peninsula, Antarctica, January.

Brent Stephenson / Leopard Seal (Hydrurga leptonyx) asleep on sea ice. Cierva Cove, Antarctic Peninsula, Antarctica, January.

Brent Stephenson / New Zealand Fur Seal (Arctocephalus forsteri) asleep on rocks. Ohau Point, Canterbury, New Zealand, October.

Brent Stephenson / New Zealand Fur Seal (Arctocephalus forsteri) asleep on beach. Kaikoura, Canterbury, New Zealand, October.

Brent Stephenson / Leopard Seal (Hydrurga leptonyx) asleep on sea ice. Cierva Cove, Antarctic Peninsula, Antarctica, January.

Brent Stephenson / Leopard Seal (Hydrurga leptonyx) asleep on sea ice. Cierva Cove, Antarctic Peninsula, Antarctica, December.

Ben Osborne / African lions (Panthera leo) large pride rests in the late afternoon prior to heading out for a night hunt, Savuti, Northern Botswana. Taken on location for BBC Planet Earth series, 2005

Ben Osborne / African lion (Panthera leo) juveniles sleeping Botswana, taken on location for BBC Planet Earth series, 2005

Ben Osborne / African lion (Panthera leo) juvenile sleeping on back, Botswana, taken on location for BBC Planet Earth series, 2005

Oriol Alamany / Magellanic penguins (Spheniscus magellanicus) mother asleep leaning on her young at their breeding colony in Seno Otway, Patagonia, Chile

Terry Whittaker / 2020VISION / Young Hazel dormouse (Muscardinus avellanarius) in coppiced hazel tree, Kent, UK. Photographed in wild under licence with remote camera (camera trap), September. Did you know? Dormice hibernate to con...

Robin Chittenden / Scops owl (Otus scops) asleep in tree, Lesvos, Lesbos, Greece, April

LYNN M. STONE / Trumpeter swan (Cygnus buccinator) asleep on frosty ice shelf on sub zero morning, St Croix River, Wisconsin, USA, February

LYNN M. STONE / Trumpeter swans (Cygnus buccinator) on open stretch of river in sub zero temperatures, Wisconsin, USA, February

LYNN M. STONE / Two Bernese Mountain dog pups sleeping in patch of woodland wildflowers (Anemone and Prairie Trillium), Elburn, Illinois, USA

LYNN M. STONE / Two Bernese Mountain dog pups sleeping in patch of woodland wildflowers (Anemone and Prairie Trillium), Elburn, Illinois, USA

Kathryn Jeffs / Antarctic fur seal (Arctocephalus gazella) pup fast asleep on beach, Antarctica, February, Taken on location for BBC Frozen Planet series

David Kjaer / Common Dormouse (Muscardinus avellanarius) asleep in a person's hand. Bentley Wood, Wiltshire, May.

Mark Hamblin / 2020VISION / Red-throated diver (Gavia stellata) adult and chick asleep on breeding loch, Flow Country, Highland, Scotland, UK, June,

Mark Hamblin / 2020VISION / Red-throated diver (Gavia stellata) adult asleep on breeding loch showing striations on back of neck, Flow Country, Highland, Scotland, UK, June,

Mark Hamblin / 2020VISION / Red-throated diver (Gavia stellata) adult asleep on breeding loch, Flow Country, Highland, Scotland, UK, June,

Mark Hamblin / 2020VISION / Red-throated diver (Gavia stellata) adult and chick asleep on breeding loch, Flow Country, Highland, Scotland, UK, June,

Mark Hamblin / 2020VISION / Red-throated diver (Gavia stellata) pair and chick asleep on breeding loch, Flow Country, Highland, Scotland, UK, June,

Kristel Richard / Konik horses (Equus caballus) wild Konik mare standing asleep next to an alert wild Konik filly, Stodmarsh nature reserve, Kent, UK, March

David Woodfall / Male Polar bears (Ursus maritimus) two asleep in day snow beds, Wapusk National Park, Churchill, Manitoba, Canada, December 2004

Diane McAllister / Two wild horses (Equus caballus) stay close to one another, with one horse looking quite comfortable and almost asleep on the other's back. The hills south of Reno, Nevada, USA, May.

Jane Burton / Chocolate Labrador Retriever puppy asleep.

Anup Shah / African lion (Panthera leo) males asleep - wide angle perspective, Masai Mara National Reserve, Kenya. August

Bryan and Cherry Alexander / Inuk asleep in hut with stove for warmth. Northwest Greenland, 1980.

Aflo / ic-03106 Young domestic kitten asleep on bedding {Felis catus}

Aflo / ic-03103 Young domestic kitten grooming on floor {Felis catus}

Aflo / ic-03101 Young domestic kitten asleep on bedding {Felis catus}

Aflo / ic-01904 Domestic cat asleep {Felis catus}

Aflo / ic-01903 Domestic cat asleep {Felis catus}

Aflo / ic-01902 Domestic cat sleeping on back in sun {Felis catus}

Aflo / ic-01901 Domestic tabby cat sleeping on car bonnet {Felis catus}

Aflo / ic-01805 Domestic cat sleeping on fallen leaves in Autumn {Felis catus}

Aflo / ic-01402 White domestic cat resting on ground {Felis catus}

Aflo / ic-00302 Domestic cat asleep on back under flower bush {Felis catus}

Aflo / ic-00301 Domestic cat asleep on decking {Felis catus}

Aflo / ic-01404 Domestic cat sleeping in sun on park bench {Felis catus}

Aflo / ic-02904 Young domestic kitten sleeping {Felis catus}

Aflo / ic-01905 Contented domestic cat sleeping on back on bench {Felis catus}

Aflo / ic-01803 Domestic cat asleep on garden fence {Felis catus}

Aflo / ic-01801 Domestic cat on back sleeping on park bench {Felis catus}

Aflo / ic-01505 Domestic cat sleeping on park bench {Felis catus}