Bonjour,
Jocool :
Je suis très surpris par ton analyse ! En effet, je n'écoutais pas de musique, je n'ai pas d'Apple TV ni d'enceintes branchées, ni disque réseau NAS. Mon imprimante est connectée mais pas branchée (prise électrique débranchée).
Je vais attendre ta réponse avant de faire tout ce que tu proposes.
Rémy :
A 2 h pile la machine s'est mise en route et à 3h48 je l'ai éteint .
Dans la console il y a des centaines de messages dont voici un extrait :
18/04/2016 23:39:41,000    kernel[0]    Wake reason: RTC (Alarm)
19/04/2016 02:00:01,000    kernel[0]    RTC: Maintenance 2016/4/19 00:00:00, sleep 2016/4/18 21:39:41
19/04/2016 02:00:01,000    kernel[0]    AirPort_Brcm43xx:

owerChange: System Wake - Full Wake/ Dark Wake / Maintenance wake
19/04/2016 02:00:01,000    kernel[0]    AirPort_Brcm43xx::checkInterfacePowerState: Check _pwrOffThreadCall!
19/04/2016 02:00:01,000    kernel[0]    Previous sleep cause: 5
19/04/2016 02:00:01,000    syslogd[43]    ASL Sender Statistics
19/04/2016 02:00:01,000    kernel[0]    00000000  00000020  NVEthernet::setLinkStatus - not Active
19/04/2016 02:00:03,000    kernel[0]    Ethernet [nvenet]: Link up on en0, 100-Megabit, Full-duplex, No flow-control, Debug [796d,0000,0de1,0005,41e1,0000]
19/04/2016 02:00:03,000    kernel[0]    05f5e100  00100026  NVEthernet::setLinkStatus - Active
19/04/2016 02:00:03,000    kernel[0]    in6_unlink_ifa: IPv6 address 0x315d2603f29f229f has no prefix
19/04/2016 02:00:03,149    configd[52]    LINKLOCAL en0: parent has no IP
19/04/2016 02:00:08,995    SubmitDiagInfo[375]    Couldn't load config file from on-disk location. Falling back to default location. Reason: Won't serialize in _readDictionaryFromJSONData due to nil object
19/04/2016 02:00:55,000    kernel[0]    PM response took 1998 ms (53, powerd)
19/04/2016 02:00:55,000    kernel[0]    AirPort_Brcm43xx:

owerChange: System Sleep 
19/04/2016 02:01:56,000    kernel[0]    00000000  00000020  NVEthernet::setLinkStatus - not Active
19/04/2016 02:00:56,000    kernel[0]    Wake reason: RTC (Alarm)
19/04/2016 02:01:56,000    kernel[0]    RTC: Maintenance 2016/4/19 00:01:55, sleep 2016/4/19 00:00:56
19/04/2016 02:01:56,000    kernel[0]    AirPort_Brcm43xx:

owerChange: System Wake - Full Wake/ Dark Wake / Maintenance wake
19/04/2016 02:01:56,000    kernel[0]    AirPort_Brcm43xx::checkInterfacePowerState: Check _pwrOffThreadCall!
19/04/2016 02:01:56,000    kernel[0]    Previous sleep cause: 5
19/04/2016 02:01:56,000    kernel[0]    00000000  00000020  NVEthernet::setLinkStatus - not Active
19/04/2016 02:01:58,000    kernel[0]    Ethernet [nvenet]: Link up on en0, 100-Megabit, Full-duplex, No flow-control, Debug [796d,0000,0de1,0005,41e1,0000]
19/04/2016 02:01:58,000    kernel[0]    05f5e100  00100026  NVEthernet::setLinkStatus - Active
19/04/2016 02:01:58,000    kernel[0]    in6_unlink_ifa: IPv6 address 0x315d2603f29f23ef has no prefix
19/04/2016 02:01:58,108    configd[52]    LINKLOCAL en0: parent has no IP
19/04/2016 02:01:58,123    configd[52]    network changed: v4(en0-:192.168.0.11) DNS- Proxy-
19/04/2016 02:01:58,581    symptomsd[184]    __73-[NetworkAnalyticsEngine observeValueForKeyPath:ofObject:change:context:]_block_invoke unexpected switch value 2
19/04/2016 02:01:58,582    netbiosd[611]    network_reachability_changed : network is not reachable, netbiosd is shutting down
19/04/2016 02:02:03,688    configd[52]    network changed: v4(en0+:192.168.0.11) DNS+ Proxy+ SMB
19/04/2016 02:02:04,390    symptomsd[184]    __73-[NetworkAnalyticsEngine observeValueForKeyPath:ofObject:change:context:]_block_invoke unexpected switch value 2
19/04/2016 02:02:50,000    kernel[0]    PM response took 1955 ms (53, powerd)
19/04/2016 02:02:50,000    kernel[0]    AirPort_Brcm43xx:

owerChange: System Sleep 
19/04/2016 02:03:51,000    kernel[0]    00000000  00000020  NVEthernet::setLinkStatus - not Active
19/04/2016 02:02:51,000    kernel[0]    Wake reason: RTC (Alarm)